Feliks Audio Elise

After several years of only owning solid-state headphone amplifiers, I decided to see what the fuss was about with tube amps earlier this year. On the surface, people seemed to be likening the technology with vinyl – something that sounded more natural to some folk but was antiquated in the modern world. Indeed, tubes have their disadvantages – a limited lifespan being the most immediate of them.

After hearing the Cavalli Liquid Tungsten at Can Jam London 2016, especially with a Sennheiser HD800, I knew there was more to it than just mere colouration of the sound. The headphone came alive with a sound that had more body than I was used to with it. I had to know more, and so earlier this year I started. First up was the iFi Pro iCan, with its solid-state to tube and tube+ mode switching. A hybrid tube amplifier that was not designed to be swappable, I found its sound to not be all that distinct between the modes. Next came the Schiit Valhalla 2, and I got a better sense of what tubes do.

Clashing directly with the stereotype of tube amps being overly warm and coloured, the Valhalla 2 added a bit more nuance to song mixes than I had heard before. Staging seemed wider too. There was something afoot here that I enjoyed, but I missed the more impactful sound of my solid-state options at the time. When I later got a Schiit Lyr 2, along with some spare tube sets to play around with, I came to understand the appeal behind swapping out, otherwise known as rolling, tubes. It was another hybrid tube amp, like the iFi, with a solid-state output stage that had only one gear to it – fast and punchy. Sure, you could put a slight spin on the sound here and there – but you couldn’t stop it from being its fast and punchy self.

When I bought the Feliks Audio Elise, I took note of the fact that it had slots for two power tubes and two driver tubes. Completely reliant on tube pairings, I was curious to see what had made this a much-discussed amplifier for tube rollers on Head-fi. I even knew someone who had one, and had spent €2400 on various tube sets. While not prepared to make that kind of investment, I wanted to understand the appeal on a basic level and felt that this was an inexpensive purchase to do so.


Specifications – From the Website

· Technical Specification - Model 2017

· Input Impedance: 100 kOhm

· Frequency response: 10 Hz - 60 Khz +/- 3 dB (300 ohm)

· Power output: 200mW

· Pre-amp Gain: 20dB

· THD: 0.4 % (300 ohm, 20 mW)

· Supported headphones impedance: 32 - 600 ohm

· Improved noise cancelling construction

· Headphones output: Jack 6.3mm

· AC: 230V/120V (power cord included)

· Dimensions: 310x205x170 [mm]

· 3 years warranty

Specifications – From the Manual

Elise is built with two 6AS7G (also accepts 6080, via the included adaptor) power tubes and two driver 6SN7 tubes. Power supply is based on a custom made stabilized toroidal transformer with electronic ripple suppression. The amplifier is equipped with automatic bias circuit, therefore no re-tuning is required after changing tubes. Please note that the optimal sound quality will be reached after approximately 30 – 50 hours of run-in.

· Impedance: 100 k ohm

· Frequency response: 10 Hz - 60 Khz +/- 3 dB (300 ohm)

· Power output: 200mW

· THD: 0.4 % (300 ohm, 20 mW)

· Optimal headphones impedance: 32 - 600 ohm

· Headphones output: Jack 6.3mm

· AC: 230V / 120V (region dependent, power cord included)

· Weight: 4.5 kg (7.7 lbs)

· Dimensions: 310x205x170 [mm] (12.2x8.1x6.7 [inch])



Build Quality & Features

After seeing the Feliks Euphoria, the flagship headphone amplifier of the company, at the London Can Jam 2017 – I saw that the designers adopted a “if it ain’t broke” mentality. The two amps are near identical in look. Both are OTL and both use the same power and driver/pre-amp tube slots.

It should go without saying that this amplifier can get really, really hot. This isn’t the heat of, say, the Schiit Asgard 2 (a class-A solid-state amp) – but is another level entirely due to the glowing tubes. Take care when handling these, Feliks themselves advise at least five minutes wait time minimum after switching off the amplifier before you swap tubes around. In fact, let me quote the manual:

Please note that tubes can reach operational temperature with excess of 150 Celsius (300 Fahrenheit) therefore tube exchange should be done with the device unplugged from AC power, after allowing the tubes to cool down and letting the capacitors discharge (minimum 5 minutes). Recommended ambient temperature for the amplifier to operate is between 15 and 30 Celsius (60 to 86 Fahrenheit).

The last part disqualifies the use of this amplifier in the summertime back in my home country, unless aided with ample air conditioning.

The actual unit is quite solidly build. I won’t do any drop tests or anything, but it looks like it will last a long time in a caring household. The volume knob is a satisfyingly smooth turn and the small LED in front is blue. There is only a slot for a single ¼ inch headphone plug, and I would recommend plugging in headphones after the amp has warmed up and unplugging before turning it off. The reason for this is that there is a loud and sudden cracking sound in the headphones if you a) turn the amp on while they’re plugged in or b) you turn the amp off while they’re plugged in. I believe Feliks told me that this was something they remedied in the 2017 version of the amp (mine is 2016), but I’d advise it regardless. I don’t even know if it would do damage to your headphone drivers, but I would advise it anyway.

Speaking of the 2017 version, I did ask them the details of how the new model differed from mine. They said that they learned some nifty engineering tricks to implement while developing the Euphoria when it came to sound isolation of the unit and decided to let those upgrades trickle down to the Elise as well. A specific example I was told was that the Elise was now less susceptible to that annoying interference from phone frequencies during an incoming call or text message. I’ve never really heard such interference in my older Elise, but people don’t usually call me anyways so.


On the back of the unit is one set of RCA inputs and one pair of RCA line-outputs – which in the manual are referred to as the “pre-amp mode.” There is a place to plug in your power cable of choice and a bright red on/off switch. I would have preferred the switch to have been in the front, but it isn’t a big deal.

Finally, the kinds of tubes that are officially endorsed by Feliks Audio to be used with this amplifier are printed on the manual:

Power tubes

Standard: 6AS7G (6N13S)

Alternatives: 6080, 5998, 6N5P, 6N5S, ECC230, 7236, CV2523

Driver tubes

Standard: 6SN7

Alternatives: 6N8S, CV181, ECC32, 5692, 6F8G

While still being so new to tubes myself, I can’t advise what else you can try with these. However, I do use a RCA 7n7 driver tube pair on the Elise – I just needed a 7n7-to-6SN7 converter set from Hong Kong.


Sound

In my review of the Schiit Lyr 2, I mentioned how any tube rolling would just modify the flavour of the sound rather than overhaul it in any large way. This is because the amp’s output section was solid state, and not flexible at all. The Elise is able to roll both power tubes as well as driver tubes, and I have found it very sensitive to changes in both. The amp is not highly transparent by any means, but it responds very well to different tube configurations. To my ears, the Elise will always embody the stereotypical outlook of tubes – warm and euphonic. It is not muddy, however, and detail retrieval is quite good. The staging is not large by any sense, but it has a very natural depth to it that does positional audio justice.

When comparing the Elise to the newer flagship offering by Feliks, the Euphoria, I found that it had a warmer tilt to the sound than its elder brother. Indeed, the terms warm and gooey come to mind – but I would argue that this is a far more articulate experience in stock configuration than the solid-state Cavalli Liquid Carbon. There is no bloat with either Elise or Euphoria, but it was apparent to me that (even in the ruckus that is show-floor background noise) the Euphoria was set up to be a leaner, brighter but more detailed sound with wider staging. Indeed, there were some visitors to the Feliks booth at Can Jam London 2017 who preferred the Elise over the flagship, simply due to its warmer and thicker sound character. If that sounds more to your liking, then you might too.

The Elise’ customizability makes it wear different hats with ease. Need a faster sound for metal and rock? Switch to the Mullard 6080. Need a smoother, more relaxing tone? Use the stock Svetlana 6AS7G. A tube amp that changes with tubes, what of it?Well, this is a tube rollers dream in its price range and build due to just how much can be done with it. Forums have threads bursting with impressions from Elise owners for a reason, it’s an affordable OTL with good baseline specifications for dynamic headphones and the ability to explore different tube pairings comes easily to it.

But, on its own, it’s a dependable amp. As mentioned before, the staging is not especially wide (although this varies, again, with different tubes) and the sound has that lusher characteristic that I now find lacking in most solid-state amplifiers. The bass does not extend especially far with the stock tubes, but this also is changed up with rolling. Rather than stretching the sound out to reveal the low-level detail in your recordings, a task that is done to varying degrees by tube amplifiers, the Elise simply seeks to add tone to your music. This is not an amplifier for detail-retrieval fiends. This also is not the amplifier for lovers of planar magnetic headphones due to its low wattage. Indeed, I paired this with a few Audeze planars and found the sound lacking compared to what I know them to do.

The aforementioned tone was eye opening to me, someone who has primarily had experience with solid-state amplifiers in the past. The Schiit Valhalla 2, which I’ve reviewed before, is leaner and brighter than the Elise and then Schiit Lyr 2 (a hybrid tube amp) is more punchy and dynamic but without the natural sound that the Elise musters. By “natural”, I mean that the Elise is not etched or hard in its treble presentation, making it so the twang of acoustic guitars and the playing of grand pianos don’t sound artificially propped for the sake of utmost clarity. The sound isn’t neutral, but I often find things sounding (within reason, depending on genre) liveinstead of a pristine studio recording. I appreciate this, and it definitely and quickly taught me about the benefits of tube amplifiers.


Before I received my Elise in the mail, I was worried about its pairing with the Focal Utopia – an 80 ohm dynamic driver headphone that I use as a reference. It was not until after I had purchased it, and after a little research online, that I found that it had a rather high output impedance compared to the amplifiers that I’d used before. The output impedance is 40 to 50 ohms, depending on where you read. Using the amplifier with the Utopia would be breaking the 1/8ths rule of output impedance; that the headphone’s impedance must be over eight times the output impedance of the amplifier. Once I plugged the Utopia in, however, my fears were put to the side. It’s not just listenable, it’s very enjoyable as a pairing – adding a smoothness to the frantically detailed and hyper nature of the Focal flagship. Was it the most ideal pairing out there? Probably not, especially if you want to take steps to enhance the detail retrieval of the Utopia through an amp pairing. But is it wrong? No. Switching to my Dragon Inspire IHA-1, a transformer-coupled tube amplifier with only 4.4 ohms of output impedance, I found the background quieter and more revealing of detail. But when I switched back to the Elise and allowed a few minutes for my ears to adjust, I found it more than capable as a Utopia pairing.


Tube Rolling

The point of this section isn’t to say that you, the reader, absolutely need to buy a bunch of tubes for the Elise to properly enjoy it – but to detail what aspects can be changed by what. Also, the stock option of the Tung Sol 6SN7s might be discontinued as per a conversation I had with one of the brothers of Feliks Audio. He told me that PSVANE driver tubes might be the way to go for the Elise company-side in the future, as it already is with the Euphoria. Easier to find tubes matches, he said. I haven’t spent a long time with PSVANE, a Chinese company making tubes these days, but they sounded good enough at Can Jam from both Euphoria and Elise.


Power Tubes

Svetlana Winged "C" 6H13C / 6AS7G

This is Feliks’ stock choice for both the Elise and Euphoria. On the Elise, it has a warm and slightly thick tone to it that gives a smoother sound overall. It is not particularly fast or heavy hitting, opting to be more laid back in approach. Vocals have a lot of body to them and bass extension is quite good, it definitely gelled with the ZMF Eikon that I have.

The major disadvantage of this pairing with the Elise is that it seems a bit veiled. Of course, this performance is closely tied to its inexpensive nature overall – but the same power tubes sounded quite different out of the Euphoria which is a testament to amp design over mere tube choices alone. The Euphoria had slightly wider staging and very inviting separation and detail retrieval. It was also leaner, to my ears, and a little more towards the bright side of things – while the Elise’s usage of the same power tubes yields a smoother, warmer and more pleasant tone that ultimately does mask micro-detail a bit.

I could not help but make comparisons to the Cavalli Liquid Carbon that I once had. I have no doubt that the Elise, using these stock power tubes, is still considerably the more articulate experience. Feliks knew what they were doing when they chose these for their two amplifiers. It’s a very good baseline sound with few shortcomings – a jack of all trades when it comes to tube options for the Elise.


General Electric 6AS7G

I’d go so far to call this the most v-shaped power tube of the three I’m talking about today. It injects a hefty amount of bass into the Elise’s sound, but not very bloated or distorted bass. While being clean, it is not all that much faster and punchier than the stock Svetlanas. It does have some weight to it, and kick drums are instantly more noticeable in mixes.

The midrange is a bit recessed, not overwhelmingly so but just slightly. I found guitars to sound a little hollow and male vocals to be emphasized over female by quite a margin. The treble extension is decent but misses out on some cymbal clarity and weight. Overall, I prefer the stock Svetlanas over this but I do appreciate just how much more of a punch these have when paired with electronic genres.


Mullard 6080

These bring the Elise more in line with my preferences these days. The Mullards are less tubey than the stock Svetlanas and are more geared towards a solid-state sound in terms of impact, dynamics and noise floor. I have no way of measuring exactly, but I can hear a quieter background with the Utopia over the stock power tubes.

Impact is an understatement of sorts as these power tubes provide a good punch to the sound of the Elise. With the Utopia, it’s a great pairing due to the headphone’s own fast and dynamic nature. I, quite frankly, hate when an amp holds the Utopia back in this regard – and so far I’ve only heard the Liquid Carbon do that by making the sound slower and a bit sluggish. The Mullard 6080s reduce the slightly thick and overly warm sound of the stock Svetlanas and open up the midrange to better detail retrieval. Micro-detail comes out better, with all the various percussion and instrumentation in Michael Jackson’s Don’t Stop ‘Til You Get Enough not being held back.

Bass is quicker on its feet, tap-dancing through the mix with precision and without any bloat or emphasis. Fans of a bloomier sound will probably not enjoy the Mullards, as it is leaner and more precise. Another noticeable upgrade from the stock tubes resides in the upper midrange and lower treble. The air region is better served by the Mullards, with string sections coming out better and faster. Grand pianos also have a less weighty and cleaner aspect to them.


Disadvantages that I can think of are probably headphone reliant in this case. While I very much enjoy the sound with my Utopia, I feel that it would hurt on the Sennheiser HD800. The treble is also more emphasized compared to the stock tubes, which is another reason why I believe the above. With a bad headphone pairing, and to those who are sensitive to treble, I feel that the Mullard 6080s would quickly become fatiguing. But for warmer headphones, I can’t recommend it enough for its price point.

Driver/Pre-amp Tubes


Tung Sol 6SN7GTB – Made in Russia

These are the, as of September 2017, stock driver tubes provided with the Elise. It should be noted that, for an additional $150, you can upgrade to Chinese-made PSVANE driver tubes and that Feliks will be making the switch to only using those eventually as they have done with the Euphoria.

The Tung Sols have a slightly tall sound. What I mean by this is that it sounds like the notes occupy more space than they do on solid-state or even other tube options. This space is not width-wise, but rather vertical. A snare hit will sound larger than life instead of a more accurate sting in a mix. I won’t lie, this has a very pleasing sound to it as there is no lack of “real estate” to be used up here. I would not call it a reference sound, but it is fun to listen to and the Tung Sols share this aspect with the Ken Rad 6SN7GTBs.

Where it differs from the Ken Rads is in the air and treble presentation. The larger-than-life sound described above is not emphasized in the bass region on the Tung Sols, but rather in the mids and highs. You will hear a guitar solo pierce through the mix with additional emphasis given to it than other tubes and you will hear vocals sound very much like an intimate live setting.

Is it an especially revealing tube? I don’t think so, and I feel that it might have been chosen to (along with the Svetlana power tubes) give the widest experience gap between the Elise and solid-state amplifiers at its price point. Stick a HD800 into the Elise with its stock tubes and you will be treated to a sound that is less reference but more musical and, dare I say, enjoyable. With the ZMF Eikon, I found that the treble peak was smoothed out with the stock tube pairing, while the Mullard 6080s gave slightly more accuracy.


Sylvania 1950s Chrome Top 6SN7GTA

I would go so far to say that this is my reference 6SN7 driver tube these days, with it almost always being used in my Dragon Inspire IHA-1 when I’m critically listening. This is mainly due to its lean sound and detail retrieval, along with some of the best extended and natural treble I have in my possession.

How does it fare on the Elise? I actually don’t prefer it compared to it on my IHA-1. Perhaps this can be chalked up to personal preferences, but I feel that the Sylvanias don’t bring as much to the table on the Elise – while they are a stronger option for the IHA-1. This is because the detail retrieval boost is minimal on the Elise and I’m used to it being far greater.


Ken Rad 6SN7GT – Black

Let me preface this by saying that this tube is overkill with the stock Svetlana power tubes. These very much need the leaner and quicker sound of the Mullard 6080 to shine.

This has the deepest and most powerful bass of all the driver tubes discussed today. Couple that with its level of low-end control and you have a fantastic pairing for electronic genres, pop and rock music. With an overall warm sound in the midrange, and a slight bit of roll-off in the treble, I would not recommend the Ken Rads for a more analytical listening experience – but it is a balls-to-the-wall level of fun in how exhilarating it is for the right genres.

My earlier description of a “tall” sound with the Tung Sol 6SN7GT is taken a step further with the Ken Rad driver tubes. A good example of what I mean is in the song Dreams by Fleetwood Mac. The single note synth-line that plays in the chorus is normally thin and distant in mixes. On the Ken Rads, however, it is very front-and-centre and sounds thicker, meatier and livelier. Those are a lot of words to describe a mere synth accompaniment to a chorus, but imagine that effect applied to all instrumentation and vocals in a track. Huge and not at all reference, the Ken Rads make up for their lack of air by making music sound bombastic with a speaker-like quality.


RCA 7n7 (with a 7n7-to-6SN7 converter)

The opposite case of the Sylvanias, I actually prefer these more on the Elise than I do on the IHA-1. The RCA 7n7 have the capability to present delicate micro-detail and have a leaner sound than the stock option or the Ken Rads. The reason they gel more with a warmer amplifier like the Elise than a leaner and more analytical one like the IHA-1 is due to the treble region becoming harsher on the latter while this aspect is masked a bit on the former. This is just speculation on my end, but it does become a more fatiguing listen on the Dragon amp.

Another strength of the RCA 7n7 is its low price compared to the other detail-head driver tubes that I have, the Sylvania 6SN7 chrome-tops. When listening to jazz, it becomes obvious that these have good tonality for cymbals, snares and acoustic instruments. They do retain some body though, less than the Sylvanias but enough to make it a good pairing for jazz, classical and classic rock.

Amping

I have to reiterate this one aspect of the Feliks Audio Elise – it is not a powerful amplifier. As mentioned before, I really did not enjoy how the Audeze LCD series sounded from this. I wouldn’t recommend using this with any planars at all, actually. I wouldn’t recommend using IEMs with it either, as its high output impedance won’t be ideal. I’m still surprised that it sounds as good as it does with the Utopia – but it’s no coincidence that many prefer this for their 600 Ohm Beyerdynamic T1’s and Sennheiser HD800’s.

Dynamic-driver headphones are the way to go with the Elise, of that I’m certain.

Conclusion

The Elise met and surpassed my expectations from a first actual tube amplifier. It has a natural tone to it and can be altered with various tube pairings. Unlike the Lyr 2, it can be morphed in a more audibly meaningful manner to suit your preferences. Indeed, it might be that it could reach the detail retrieval prowess of its elder brother, the Feliks Euphoria, or even my Dragon Inspire IHA-1 with the right tube pairings – but I did not pursue those and will leave such discoveries to other owners. I do recommend reading the Head-fi threads about this amplifier though, there is a lot of interesting discussion going back several years.

One consistent thing about the Elise, no matter the tube pairing, was its ability to have a very smooth and enjoyable sound. After months with it, I understand fully why some would find it immediately more enjoyable than the Euphoria when they first heard the two at Can Jam. While the Euphoria is not sparse in tone, having its own strength and body, the Elise is more akin to what some people just seem to expectfrom a tube amplifier – with its stock power and driver tube pairing. It’s smooth, laid back and quite musical. It doesn’t try to be a low-level detail-resolving monster like some other tube amplifiers, but aims to be for those who want a more organic experience than their solid-state options with a gentle bloom in the bass and some midrange weight.

Feliks Audio Elise​

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The Right Stuff
Roll credits.  Well, not exactly -but the point is that the Feliks Audio Elise is a darned good piece of equipment. And with its recent update, this cult favorite has only gotten better.  The 2017 Elise features reduced background noise and a new three-year warranty, two very welcome changes to an already excellent product.  Those who have read my reviews in the past will know that this isn’t my first encounter with Feliks Audio.  This Polish audio company previously impressed with a budget tube offering in the form of the Espressivo, a smaller 6N5P/6N1P tube setup that predates the Elise.  Featuring a musical and dynamic sound with good punch, the Espressivo offers an immediately entertaining house sound that was quite captivating.  Needless to say, the Espressivo made a big impression at its then $349.00 USD price point (currently retails at $449.00 USD) and received deserved praise.  There were several points of note though.  The Espressivo’s sometimes hot upper range, mediocre detail retrieval (and smallish soundstage) were limiting characteristics.  The Sennheiser HD 800 pairing, as some mentioned, was not particularly noteworthy -partially due to the fact that the Espressivo failed to realize some of the headphone’s key qualities.  In this sense, there was room for improvement.
 
First released in late 2014, the Elise is a single-ended, OTL tube amp successor to the Espressivo, featuring a better stock setup of 6AS7G(6N13S)/ 6SN7 tubes and an upgraded transformer.  It has amassed a dedicated community following (which can be found at this most recent thread).  The thread contains exhaustive notes on tube-rolling and modifications, as well as links to past threads/ collections of information. The Elise also has the rather unique distinction of being hailed as one of the best-pairing amplifiers with the Beyerdynamic T1 headphones.  The latter point is of particular interest to me, as I am indeed a fan of the Beyerdynamic T1 Gen. 1 (21,000+ serial).  My thoughts are surmised in the confident conclusion that this is one of best T1 pairings I’ve heard to date.  Before proceeding with this review, it is worth mentioning that failing to use a recommended tube combination can lead to damage to the amplifier, which may void its corresponding warranty. The Elise is currently available at $849.00 USD with the standard Tung Sol Drivers or at $999.00 USD with the upgraded Psvane tubes, with both options being offered directly by Feliks Audio. It will take 4-6 weeks for a typical order to be fulfilled (lead time will vary, from my understanding). Shipping is handled via EMS. Poczta Polska in Poland, and local carrier upon arrival.  Email communication is responsive and helpful, so feel free to contact Feliks Audio before making your order.
 
Disclaimer
As with the Espressivo, the Feliks Audio Elise was provided directly from Lukasz @ Feliks Audio for the purposes of this review.  I have once again been told that I can keep it, and have now had it on hand for over a month.  Some technical issues delayed the release of this review, and the folks over at Feliks Audio have been very patient imdeed!  I do apologize to those whom have been waiting for this review to come out -it’s been a while in the making.  As always, I am neither a paid affiliate nor an employee of Feliks Audio.  In addition, I do reserve the rights to the media used in the review, so do contact me if you wish to reproduce any part of the writing or photography seen here.  Apart from that, I thoroughly enjoyed this amplifier, and hope that you will come away from this review with a sense of what the Elise can do.  Do feel free to comment below - I try to stay updated, but if for some reason you cannot reach me, just shoot me a PM and I will try my very best to answer your questions.  Sometimes things get lost/ I accidentally miss emails, so following up never hurts.
 
 

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The Elise arrived in a heavy cardboard box, once again sealed with black tape bearing the company logo and name.  Opening the box will reveal the amplifier encased in Styrofoam and loose marshmallow bits, with tubes stowed away in the hollow center area.  The tubes are wrapped individually in Styrofoam and none of mine were damaged during the shipping process.  There was just a slight bit of oxidation on one of the tubes, which was fairly quickly resolved with a good old eraser.  There is also a small hand-signed card to add a personal touch, and a short manual to get started with.  Overall, nothing too complex and the amplifier should be up and running within a matter of minutes.  A power cord is included.
 

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The Feliks Audio Elise is a great looking headphone amplifier. Cutting a svelte figure in black, the Elise tucks away nicely in almost any setup.  Whether it’s meant to operate in the background as a pre-amplifier, or as a centerpiece in a headphone-based chain, the Elise looks suitably great in almost all situations.  It’s an understated but nonetheless elegant look that simply works.  Starting from the top, users will find a chrome plaque featuring the Feliks Audio logo and name.  It is an improvement over the brass one found on earlier iterations of the amplifier, as it now matches the reflective portions of the upgrade Psvane tubes for greater aesthetic continuity.  The transformer enclosure stands at 9.00 cm tall with an associated cross-sectional area of 10.5 cm (width) x 17.5 cm (length).  Corners are slightly rounded with smooth leading edges.  At the base of the transformer enclose are a set of six 3.70 cm x 2 mm slits, paired in three groups of two and evenly spaced apart.  The depth of these slits also indicated that the aluminum enclosure was about 1 mm thick. The first row of tubes (positions 2 and 3, manual) should be equipped with the power tubes, and the second row (positions 1 and 4, front) with the driver tubes. Driver sockets are secure without excessive amounts of play.  The face plate is 1.00 cm thick.  Appropriately balanced and far from being gratuitous.  On the front is a single headphone output (quarter-inch) and the volume pot.  Operation is indicated via a single blue LED, and the model name/ Feliks logo can be found engraved as well.  The rear of the unit features a single set of RCA inputs, a single set of RCA line outputs, and a power switch/ fuse socket for AC power connection.  Overall weight is 4.5 kg, and general dimensions are 31.0 cm x 20.5 cm x 17.0 cm.  The unit is elevated by a set of polished metal feet, and flipping the unit over reveals a ventilation cut-out in the shape of the Feliks Audio logo.
 
Overall the aluminum chassis on the Elise is a great improvement over that found on the Espressivo.  Gone is the odd font and slightly quirky design of the Espressivo and in its place, a more mature looking amplifier. There are no glaring problems on my unit -but there are quibbles.  The volume pot is scuffed (perhaps a B-stock unit), and rotating it does cause it to rub against the face plate at times.  The latter point does not produce an unacceptable amount of friction though, and it does not seem to permanently scratch the faceplate.  On the topic of the faceplate, the block is a bit of a fingerprint magnet, and because it seems to have been finished slightly differently from the rest of the chassis, this does become apparent after a while.  Feature wise, noticeably absent on the Elise is the option to have multiple inputs.  Granted, this hasn’t been a major issue for me personally, but for those using multiple DACs, switching inputs will be a little bit of a hassle. I'm hoping to see this feature perhaps reintroduced in future iterations/ models.
 

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The first order of business here was to determine the output impedance, since this specification isn’t stated on the website.  In comparing the voltage output unloaded/ loaded for given signal, I found that the output impedance of the Elise ranges in the 54-ohm region. Previously mentioned output impedance numbers on community forums have been 40 ohms/ 50 ohms, which is generally in line with initial expecatations. This isn’t an entirely surprising finding, considering that this is a single-ended OTL tube amplifier.  As name suggests, output transformerless amplifiers lack an output transformer.  The design philosophy here being that forgoing the output transformer will result in lower distortion.  One of the considerations then is impedance matching and the effect of dampening factor, especially for dynamic driver headphones that can at times seem visible (and audible) FR changes as a result.
 
 
The Elise is a rather efficient amplifier from my understanding, and will drive low impedance loads as needed.  I had mixed success using low impedance headphones/ earphones, and I’m sure that given the large inventory of headphones most users here have, it’ll be up to the individual to determine what works and what doesn’t.  I tend to stick to the1/8^th rule for simplicity’s sake (headphone impedance should safely be 8 x the output impedance), so both the Audio-Technica R70X and Beyerdynamic T1 come away squarely in this sense (FR isn’t visibly affected for either of these headphones).  For the record, none of my impressions will be based off of IEMs/ low impedance headphones -doing so doesn’t accurately portray the Elise’s intended design goals in my mind. I’ve seen reviews/ posts where IEMs like the Noble K10s were plugged into this amplifier.  Not my intention to be contrary -but this does not constitute a wholly fair evaluation of a great piece of equipment in my opinion.  For those who are indeed curious about my general thoughts regarding the use of IEMs with this amplifier – noise floor may be an issue for the more sensitive ones, and what seems like transformer hum can be heard softly in the background.  Listening subjectively – I found some pairings to be oddly tizzy and harsh, with sub-bass roll off and a lack of general cohesiveness.  No such issues persisted with the higher impedance headphones. 
 
I’ve done some basic RMAA measurements as well, nothing too surprising here. RMAA results are only as good as the equipment used to perform the tests, and there has been a decent amount of coverage on its limitations and weaknesses. Currently, I am utilizing an Asus Xonar U7 external sound card (line-in mode). The ADC is a Cirrus Logic CS5361-KZZ that is capable of 24/192 w/ a 114 dB dynamic range. It uses a 5th order MBT Delta-Sigma Modulator, and attains low levels of noise and distortion. For those curious, the DAC is the equally capable CS4398-CZZ. Please find my results below. The 32 ohm load is the Samson Z55, 470 ohm load is the Audio-Technica R70X, and the 600 ohm load is the Beyerdynamic T1.
 

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At A Glance
I plugged the Beyerdynamic T1 in with high expectations (and a certain degree of impatience).  In fact, I recall the tubes still tingling slightly when I gave the Elise its first go (not recommended).  Needless to say, I was quite immediately impressed -the hype had delivered.  Tempering my initial excitement, I sat myself in a chair and listened. And listened.  A hundred album playthroughs later, my original impressions came through mostly intact.  The Elise is an incredibly pleasant amplifier with an easily likable house sound.  It carries a touch of warmth, especially through the midrange, with well-extended highs (tad bit of sparkle) and a solid lower frequency performance.  This isn't a sloppy tube amplifier - in fact, it does rival my LC in terms of speed (though the difference becomes more apparent with balanced output).  Staging is excellent, and this is an amplifier that I believe would pair very nicely with a lot of different pieces of kit.  Headphone recommendation wise – it worked splendidly with the Beyerdynamic T1 (and I imagine the HD800 wouldn’t be too far behind either).  Lending a pinch of warmth to the midrange and more depth to the lower-end makes for a great combination.  Upper frequencies a tad softer than my usual preference.  The Audio-Technica R70X, which has quite a markedly different tonality than the T1, also worked very nicely, a further indication that this was a generally balanced amplifier.  Once again, the midrange was delivered upon, but the bass was a touch slow.  Apart from that, it was still a very respectable pairing.  I did also notice that the Schiit Bifrost Multibit was well represented with this amplifier. The somewhat exaggerated staging of the multibit DAC became better connected through the Elise.  The image is “continuous” and cohesive, and the general soundstage is wide with good depth.  This stands in contrast with other pairings, especially with the iFi iCAN, where the sound was occasionally presented as coming from the extreme sides with a strong but nonetheless singular center image.  As far as tube-rolling goes, there have been simply too many variations and experiments conducted thus far to be easily surmised.  If you’re planning on getting an Elise look to the thread linked in the introduction for a jumping off point.
 
Soundstage And Imaging
Unlike the Espressivo that preceded it, the Elise has a comfortably large soundstage with good width and depth.  This is a significant improvement over the Espressivo, and reason enough to consider entertaining the notion of an upgrade.  Returning to Vangelis’ "The Tao of Love", the panning sequences are well-executed and provide a great sense of height as well.  There was no clipping in terms of width, which comes as a great relief.  Synthesized melodies aside, more traditional orchestral standards such as Bizet’s "Carmen, Act 1 (Prelude)" performed by the Slovak Radio Symphony Orchestra put on display the capabilities of the Elise. Separation between the respective sections is excellent and imaging is good.  Even in the more difficult sections, the Elise was able to discern between sonic components as needed.  This is more or less due to the Elise’s respectable levels of detail retrieval, which is a clear improvement over that of the Espressivo.  Macrodynamics on the Elise are however are not as pronounced as on the Elise, most like owing to the softer bass and less sparkly highs.  This is an acceptable trade-off and one that comes out in favor of the Elise for most situations.
 
Bass
The Feliks Audio Elise has a reliable and predictable bass section.  It definitely has more mid/upper-bass emphasis than sub-bass, and qualitatively tends toward being a little softer.  With the T1, this adds a bit more heft in the lower frequencies, which is a welcome addition to the otherwise tight and resolving sound.  Bossa Nova tracks like "Wave" by Antonio Carlos Jobim felt adequately presented and engaging, and Sebastiao Neto’s bass lines are heard clearly through the rest of the composition.  Sub-bass extension is okay, but not breathtaking.  While spending time with Jean-Efflam Bavouzet’s excellent interpretation of "La cathédrale engloutie" (Debussy), I noticed that the sonore sans Dureté was not as visceral as I would’ve liked.  It was by no means poor, but having explored this section in great depth in the past (especially via the TH-900/ Z1R), I knew there was more information that could be conveyed with greater presence.  Textural quality in the sub-bass region was correspondingly normal.
 
Midrange
The Elise really starts to shine in the midrange.  I think a term that has been used before by users is “euphonic”, and I have to agree.  The sound is liquid, with slight warmth and good body. It’s overwhelmingly pleasant, and quite addictive. Starting with the lower midrange, I began my evaluation with several tracks from Tony O’ Malley’s Audiophile Selection.  Before I endure the collective wrath of music enthusiasts, I will clarify that I did not get this album simply because it said audiophile on the front but rather because I felt that it would make for some great evaluation standards, and also because I appreciate Tony O’ Malley’s rougher, guttural voice.  It is a smooth listen, though certain textural cues aren’t as emphasized as I would like.  It has a slightly rounded taste, though by no means does it have the “Z1R treatment”.  Female vocals are a simple joy with the Elise.  Once again returning to Antonio Carlos Jobim’s "Aguas de Marco", I am utterly impressed by the energy of the sound, and the Elise’s ability to maintain good levels of clarity while delivering a smooth sound.  It leaves an impactful and lasting impression.  The way Jobim’s breathy timbre contrasts with the almost glossy, unified sound of the vocal support is a positive indication of the Elise’s rendering capabilities.  Norah Jones entered and exited with grace, in what could only be described as one of the most soothing listening sessions I've had.
 
Highs
The highs on the Elise have a touch of sparkle, but never come off as being hot.  This point is important when considering the  on the Espressivo (especially with certain choices of tubes).  The opening of Paradise City is a head-banging experience.  The guitars have a nice electrical sheen and Axl Roses’ distinctive falsetto/full-voice combination (not going to open up that can of worms) powers through the track.  This kind of flexibility in the Elise is very much welcome, especially for people like myself who tend to listen to a wide variety of music.  Looking into other genres, violins such as those found in Schubert’s String Quintet in C Major have good bite, and do convey an aggressiveness fitting for the piece.  The bow lifts are choppy and abrupt, but positively so as the piece does indeed call for this style of playing.  In general, the Elise delivers on sparkles as needed without becoming tiring. There is a nice amount of air at any rate, and the amplifier certainly does not suffer from congestion and resulting incoherence.
 
And What Am I Listening To?
This isn't necessarily reflective of the albums that I find to be best suited for this amplifier.  It's more of an eclectic mix of whatever I find queued up in my playlist at the time of writing.  I certainly found it entertaining to write about at any rate.  It's a candid look at just what high-performance audio gear is being used for (for better or for worse).
 

This is one of the best ACJ albums in my opinion, and an excellent demonstration of Jobim’s breadth as an artist.  In a carefully reinventive fashion, Jobim brought Bossa Nova into the modern era with a polished production featuring trombones, saxophones, acoustic guitars, and that ever-present bass.  It is a combination that would have fit right into a chic 70's cocktail party replete with odd fashions and strange drinks.  Not to mention a nonstop whirlpool of classy cigarette smoke.  I’m happy to have been able to secure a Blu-Spec CD release from the CTI Supreme Collection while in Japan -it is the best version I have come across thus far.  This album is a great way to enjoy the Elise in my opinion.  The opening track “Tereza My Love” is rendered excellently with the amplifier’s staging coming into play as the interestingly mixed instruments come into play.  "Brazil" is a simple joy as the T1/ Elise combination powers through with fluidity (and resolution).​

 ​

The rest of the pieces fall into place as the amplifier traversed through with smooth ease and good weight.    
 

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The incredibly successful art rock album from the well-regarded Arcade Fire is an example that rock is still alive (maybe not so well) in this day and age.  The imaging and soundstage work to the amplifier’s benefit on title track “Reflektor”, with the vocal panning being hauntingly well done.  The Haitian rara influences are present and definitely accounted for, and the fairly complex composition has been done justice via the Elise, which doesn't fail to handle complex sections.  If there was one complaint, it would be that the tracks could use just a little more edge, with more impact in the lower frequencies.  The Elise's euphonic qualities aren't exactly optimized for this genre of music.  “We Exist” was a certain blast – I had a great time picking my way through the guitars, vocals, piano -all while being able to appreciate the melody as a whole. It's simply good.
 

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Yes, I listen to Calvin Harris as well.  What? Crappy recording quality (which for the record, isn’t all that bad)?  Not audiophile enough?  Go away, this guy churns out summer anthems faster than an audiophile can switch gear.  And fairly good ones, too - if their generic nature can be discounted.  My favorite track from this album has to be “Pray To God”, featuring HAIM.  The Elise definitely did not disappoint -the drop has weight and decent intensity.  For house that is. Okay, trance and dubstep fans can stop laughing and excuse themselves now.  The weight of this judgement is getting to be oppressive. The vocals have nice presence and the work of the Haim sisters certainly isn't going unnoticed.    “Faith” is another nice track coming from Harris himself.  It has a little bit of edge, but then again any respectable amped-up EDM album needs a semi-reflective piece doesn't it?  And we certainly couldn't conclude without mentioning that Ellie Goulding is still "Outside".   Quick, someone open the door!  I should also mention that the R70X-Elise combination on this album is really lots of fun.
 

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The Elise is a great amplifier.  At its current price for both the base and upgraded versions, it really is hard to find something that does so much right.  The build quality on the Elise is excellent, and the  well finished and machined chassis makes for a great talking piece.  The current tube setup opens up serious rolling options, and near endless modding opportunities (proceed at your own risk!)  Perhaps the greatest draw for me has been the well-executed Feliks house sound, which is pleasant and well-balanced with a touch of warmth.  It's a clear step up over the Espressivo, providing obvious improvements in key areas such as the treble, soundstage, and general resolution.  I will conclude by saying that if you've a Beyerdynamic T1, it would be absolutely criminal to not give this amplifier a try!  
 
 
 

Firstly I would like to thank Feliks Audio for the loan unit for review, I have been using it for the past month and a half roughly and it has been thoroughly burnt in which is essential with valve amps.
 
Gear Used:
Marantz CD-52 > Coaxial > Matrix Quattro II DAC > Elise > Hifiman HE-500 / Beyer T1 2^nd Generation
Audio Opus #1 > Optical > Matrix Quattro II DAC > Elise > Hifiman HE-500 / Beyer T1 2^nd Generation
 
 

 
Tech Specs:

1. Input Impedance: 100 kOhm
2. Frequency response: 10 Hz - 60 Khz +/- 3 dB (300 ohm)
3. Power output: 200mW
4. Pre-amp Gain: 20dB
5. THD: 0.4 % (300 ohm, 20 mW)
6. Supported headphones impedance: 32 - 600 ohm
7. Headphones output: Jack 6.3mm
8. AC: 230V/120V (power cord included)
9. Dimensions: 310x205x170 [mm]
10. MSRP: $699

 
Packaging, Accessories and Build Quality:
The Elise comes in a plain card box, with cut out polystyrene to hold it all securely in place, the valves come in boxes and bubble wrap and are numbered. The product comes very well packaged and nothing can move or break during shipping. But there is no commercial packaging as such, but that makes no difference in my opinion.
 
Accessories are none, but this doesn’t need any, it comes with everything you need, the amp, valves, power cable and a manual (which shows where to insert each valve)
 
Build quality is impeccable, no imperfections in the finish of the amp, all the inputs and the headphone out are solid, and the valve sockets are tight. And to top it off it looks fantastic with a very understated matte black finish, and symmetrical valve placement. There are cooling vents on the bottom of the unit, feet are pre attached and it all works as it should. The volume knob has a small line indicator for the volume, and the volume pot is very smooth to operate.
 

 
Features:
This is an OTL valve amp, it has 1 set of inputs and 1 set of outputs, I would have liked it to have 3 inputs like its sibling the Espressivo, but I can get by with just one set of inputs. There is a set of RCA output sockets which mean this can be used as a pre-amp, a nice little feature.
 
There is a small blue light that indicates the unit it on, just below the headphone jack (not that you need it with glowing tubes), this amp does get very hot as you would expect, so don’t leave flammable materials resting on it, but I have ran it for 8hrs and more and it has been fine.
 

 
This amp is suitable for high and low impedance headphones, however it does work best with high impedance headphones like the Beyerdynamic T1, but also works well with the Hifiman HE-500, which are low impedance but need a lot of power.
 
The Elise has incredible valve rolling capabilities with the use of adapters or without, making this very tuneable to your tastes. The stock valves are a great starting point though, sound excellent and give you a good idea of what valve amps sound like.
 
Here are the recommended alternatives to stock valves:
 
Power tubes
Standard: 6AS7G (6N13S)
Alternatives: 6080, 5998, 6N5P, 6N5S, ECC230, 7236, CV2523
 
Driver tubes
Standard: 6SN7
Alternatives: 6N8S, CV181, ECC32, 5692, 6F8G
 

 
Sound:
I will mainly be comparing the Elise to its sibling the Espressivo which I own, my reference amp of choice is the Matrix Quattro II internal amp, it is very balanced and neutral.
 
First let me tell you that the Elise has plenty of gain, and drives the T1 with ease, and even drives the HE-500 with authority. I have tested turning up the volume with the HE-500 and no clipping can be heard throughout the range, most of my listening was done at around the 10’oclock mark with the HE-500. The Espressivo doesn’t drive the HE-500 as well, and clipping occurs at 2o’clock onwards (louder than anyone would want to listen to however) and I find the Espressivo has more gain (9o’clock normal listening level) but less authority in raw power.
 
The Elise has a smooth and full sound, it brings a sense of euphoria to your headphones and music of choice. It does this however with no effort, it never strains to bring out the detail in the music, or the volume. Compared to a more neutral amplifier I find the lows are fuller, which in turn fills out the mids slightly without masking the finer details in your music. I find this is where you can tell apart the budget valve amps from the serious ones, it has the warmth of the valves but it is subtle and doesn’t smear the details or sound, it just slightly enhances it.
 

 
I know there are purists out there that want wire with gain, and then there are people like me who just want to sit back and enjoy the music, with this amp I find myself just enjoying it, and not analysing the sound of my headphones or the amp.
 
It brings out a sense of grandiose, and emotion in the music you are listening to, it doesn’t hurl detail at your face, but you can hear them if you listen. I also find it does not lack power, I am a big fan of rock, post-harcore and metalcore, and with the HE-500 there is speed and precision without harshness.
 
I just feel my headphones sound more natural and effortless with a hint of warmth from this amp. It is very hard to describe the exact sound of this amp, as it is such a good amp for the money, it is warm but not overly smooth, it is powerful and extends to both extremes very well, I think the best way to sum it up is effortless and non fatiguing. 
 
Compared to the Espressivo, I find the Elise smoother, the Espressivo sounds a little more detailed and airy, but doesn’t have the power or resolution of Elise, the Elise sounds more effortless and less strained. The Matrix Quattro II sounds sterile in comparison to the Elise, the Elise just makes everything sound bigger and fuller, but still separate and detailed. The Matrix Quattro II is great for referencing but for actual enjoyment the Elise is so much better.
 

 
Conclusion: From the build quality, to the customer service to the sound everything about this amp is good, and for the $699 asking price it is an incredible deal indeed. The rolling capabilities are huge, but the stock valves are a great starting point. It looks as good as it sounds too, they have managed to make it functional and aesthetically pleasing all in one. The sound is warm and full, with a wide soundstage and a very easy to listen to sound, yet it doesn’t stumble when it comes to technicalities either. It has the emotion to bring out the subtleties in Diana Kralls - The Girl in the Other Room, and the power to play Story Of The Years – Black Swan without faltering.
 

 
It works well with most headphones too, of course you won’t want to use sensitive IEM’s with it, but most full size headphones will work well, it even works well with the slightly warmer sounding Fostex TH500rp, but does play better with neutral-bright sounding headphones. And valve rolling allows you to match the sound of the amp to the headphones to some extent, making this a truly versatile amp.
 
All that could be added is more inputs.
 
Sound Perfection Rating: 10/10 (Incredible value, impeccable build, impressive sound)
 

 
 

Elise by Feliks Audio
 
In the Spring of 2015, Elise came to Sydney Australia. It has been almost one year since Elise was born.
 
I have watched the video, read others impressions of it and followed the thread created by hypnos1. It was fascinating to see ideas discussed by the good folks in the thread and passed on to Feliks Audio, a small boutique Polish tube amplifiers business setup. Their website shows a few very nice looking stereo tube amplifiers. In the months of late Jun – Nov 2014, Feliks Audio started on the design that went through several iterations with feedback from the Head-Fi community. Eventually the 1^st prototype was shown and she was named Elise. hypnos1 received the 1^st Elise being build and was delivered to him on the night before Christmas. I bet he missed the Christmas turkeys and forget to open all his other presents.
 
In my hands now I have the box that contains Elise. Carefully I opened it to reveal a beautiful powder coated black steel enclosure of the highest quality I have ever seen.  The design is one of simplicity and grace. There’s not a screw on the upper part of the headamp. The front facia is simple with the large volume knob placed centrally and the headphone jack to the left. On top the sockets for the power and driver tubes are positioned symmetrically. At the back, the custom made stabilized toroidal transformer sits looking very big and purposeful.
 
I inserted the supplied Russian 6H13C power tubes and Tung Sol 6SN7GTB reissue driver tubes, flick the power switch on and let the tubes warm up. With the jack inserted I strap on my HD650. I chose to listen first with the HD650 because it’s a headphone that has gathered more attention than any other headphones I know. It’s also the headphone I love. I have with me the NAD D1050 DAC/Amp, which is use as a DAC for this purpose. My source is my dedicated iMac with Apple lossless file stored in iTunes. I have Audivarna Plus sitting on top of iTunes.
 
I started listening to Local Hero by Mark Knopfler. This is my favourite tune. It is timeless, a real classic. There’s a sense of sadness as well as joy just listening to it. The guitar works of Knopfler is just amazing. Elise portrayed that well. I could hear Mark positioned in the middle, the crowd clapping and whistling. The saxophone player sits to the left and slightly behind. The drums kicks in and gradually gaining impact and momentum. I finished the song breathless.
 
Next I listened to Preacherman by Melody Gardot. I sat transfixed as my ears got a good massage. My sensory organs were being tickled pink. I have listen to this song countless times but never as involving as I heard it through Elise now.
 
Not satisfied I needed to know how it sounded with hard rock. For Whom The Bells Toll by Metallica really rock my brains. Elise has the power and the guts to grab my HD650 with both hands and wring every ounce of sonic juice out of it.
 
I needed to listen to Nine Million Bicycles by Katie Melua. Nine million bicycles in Beijing and 6 billion people in the world. I fell in love with Katie Melua. The wordings and her voice, it’s just too beautiful to listen to.
 
Being a Jazz and vocals lover I have to listen to Diana Krall – California Dreamin’. I’ve never heard Diana so close and intimate. I was in for a sensory treat. Her voice is so husky and seductive. As the instruments sets in I look around me thinking I heard something. It was the song going in my head and Elise made it so real.
 
I finished off my listening with Fur Elise by Beethoven. The piano chords are crystal clear and struck with authority. This timeless classical song is a fitting tribute to Elise.
 
These are my 1^st impressions of Elise.  The tubes and amp aren’t even burn in.
 
Months before I have been raving about the sound I got out of my Darkvoice 336se and HD650. I felt at that time it sounded really good. Surely it would be hard to improve on that combo without spending a lot more. Well I was so wrong. Elise provides a totally immersive sonic experience. I’m at a lost for words on describing the music I’m hearing right now. It is fast, lively and dynamic for a tube amp while at the same time there’s no mistaking the tube sound so beloved of tube headphone amplifiers. Equally present are the glow, lushness and alluring warmness that draws you in for a long night of listening to music.
 
Just before finishing I swap my headphone to the Hifiman HE560. WOW. All that I dislike about this headphone being bright disappeared when paired with Elise. I get the warm and lush tones that I love in addition to the sparkling mid range and very clear high notes. It was a most linear presentation throughout the frequency spectrum. All my fears about Elise not being able to power a planar magnetic and difficult to drive headphone with low efficiency like the HE560 is gone on the very 1^st notes. My volume control was only at 9 o’clock. Elise has the power and finesse to drive the HE560 to perfections. I’m SOLD.
 
Wait …I’ve already bought Elise.  
 
My head-fi setup

 
Mazda 6N7G and Tung Sol 7236

 
ECC31 and Chatham 6AS7G

 
Mazda 6N7G and Chatham 6AS7G

 
Philips Miniwatt FDD20 and Tung Sol 5998

 
Philips Miniwatt FDD20 and Chatham 6520

 
FDD20 / ECC31 with Chatham 6AS7G

 
Lorenz C3G and Tung Sol 5998

 
Philips Miniwatt FDD20

 
6xEL3N

About me and my setup (including this Elise):

I've been lurking on Head-Fi since 2009, but only officially joined in 2012. Since 2012 I've made the transition from redbook only to being a big fan of high definition music, including DSD. My collection of audio gear has exploded in the last year from being a Cowon D2+, a pair of HiFiMan RE0 IEMs, and some KRK KNS8400s to everything that is now in my profile, and it is glorious!

Headphones: Primary: HD600 (tights mod) with HD650 cable, also have run HD800, HiFiMan HE-500 and HiFiMan HE-6
Integrated Amp: Cambridge Audio azur 540A
DAC: LH Labs Pulse X-Infinity
Interconnects: Atlas Integra to Elise from Pulse X-Infinity, Van Den Hull MKII to azur 540A
Power Cable: Mains Cable's R Us Screened 1.5m power lead
USB: LH Labs Lightspeed 2 1m to iUSB3.0, LH Labs Lightspeed 2 USB 2m from iUSB3.0 to LH Labs Pulse X-Infinity
Speakers: some nearly 30 year old Mordaunt-Short bookshelf speakers won off of fleabay for £20 (pretty good for the price)
Speaker wire: generic multistrand OFC copper.

Most of my components serve to lower the noise floor, especially the USBs and the power cable. Differences were detectable by the non-audiophile spouse.

I won this Elise in the Cambridge UK Head-Fi meet and have used it with the stock tubes for about four months, but I'd only been using it as a preamplifier until today, when I got my adapters for my Lorenz C3G tubes.

Impressions

This amp has been brilliant the whole time I've owned it as a pre-amp. It improved the noise floor and imaging of the azur 540A and they have worked together nicely. However, when I listened to the Elise out of the headphone amp using the stock tubes, it lacked top level bass and treble extension, and was a bit too warm for my liking. I did a quick back and forth between the Elise and my Geek Out 1000 (I didn't have the V2 yet) for about an hour of listening and preferred the crispness and tight sound of the Geek Out 1000 to the Elise. This led to my head-amp function of the Elise going unused for four months.

I've been looking forward to trying the C3G as a driver tube for the Elise for about a month, and today my wait ended when an adapter made by an early adopter of the Elise arrived. Boy, what a difference the tubes make! These suckers have tightened the bass, cranked up drum and bass impact, and extended the highs while increasing soundstage depth and width. The headphone out may be a little bright now (satisfyingly detailed but a bit fatiguing), so I may look for a warmer/richer set of power tubes to run this. Today I've enjoyed the heck out of Pink Floyd - The Wall, Lou Reed - Transformer, and now Crosby, Stills and Nash - Deja Vu. I'll be listening some more and sharing this tube setup at the next meet that I can bring it to.

I highly recommend checking out the Elise threads:
http://www.head-fi.org/t/732875/feliks-audio-elise-previously-6sn7-6as7g-6080-prototype
http://www.head-fi.org/t/782754/feliks-audio-elise-new-thread
http://www.head-fi.org/t/765460/feliks-audio-elise-tube-rolling-guide-6sn7-6as7g-6080-5998

There are also many other references for tube rolling, and the Elise is compatible with a wide range of tubes, many of them inexpensive for your rolling and wallet pleasure. I've got 6n23p, 6n1p and C3G tubes with adapters. I haven't tried rolling the power tubes yet, but it may be next for me. There is a really nice community around this amp and the folks at Feliks are a family operation with great customer service, I had some enquiries and they were very helpful.

Happy listening!

Blasting the HE-6

This weekend we had a mini-meet and brought one of the most hard to drive headphones out there, the HE-6, the volume rarely had to go past noon and it sounded amazing. The HE-6 sounded best out of another amp that was present, the First Watt F6 power amplifier running speaker taps, which had a little bit better bass but the Elise did an impressive job running the vaunted HE-6 (they are my favourite headphones by sound quality). I have a feeling that with upgraded power tubes that the Elise can approach that level, and the Firstwatt F6 is worth £3000. The Elise punches way above it's weight class when given the right tubes. The C3G upgrade with hypnos1 custom adapters took this to another level, but I wonder how far it can go with further upgrades. This is an extremely good value piece of kit.

This weekend it had the LH Labs Pulse X-Infinity acting as a pre-amp, and I think that ups the performance even further. All I know is it sounded glorious.

Review: Feliks audio Elise (stock Svetlanas nos 6as7g power tubes, jan Sylvanias nos 6sn7wgta drivers, selected and chose by Luzasz) on  Sennheiser hd800
 
First of all:
About my HP setup:
- Elise has now full break in (100/110 hours); I feel after some 60/70 hours of running sound didn't change any more
- another head-amp: a diy SS one, with added 41ohm resistances at the output to perfectly match the hd800 impedance (I tested R values from 6.8 to 100ohms)
- main source: CDplayer Teac PD501HR; not a high-end gear but very neutral, detailed, with a wide bandwidth
- interconnect: DIY pure single stranded silver wire, silver plated RCA plugs
- stock hd800 cable
About the hd800:
I regard its only flaws being
- a bit too much rolled off sub-bass range but only vs bass champions HP
- the well-known 6kHz peak:  a light personal anaxilus mod on my hd800 reduces somewhat this peak without rolling off the upper treble too much; it is made of open cell foam + thin felt, thus something a bit different than the classical closed cell foam felt; I tested around twenty materials/shapes _ with and without measures _before staying at the open cell foam ring + felt sticked only on the center metal ring. In my experience any mod does nibble transparency, one must find the one that nibble the less. For the purpose of this review I listened at my hd800 with and without the mod
- a rather lean/rising global sound, resulting in a loss of flesh and presence; the mod nicely adds weight to the sound, that's intrinsically important... but also because it makes the HP more forgiving to dry recordings
Otherwise a faultless HP with pin point imaging, wide soundstages and clean clean clean overall sound; just a few words for those regarding  its " too large of a soundstage width": listen to   monophonic tracks to realize it doesn't lie in this area.
About me:
- my long time main hobby is to design passive filtered hifi speakers. So I'm certainly more objectivist than subjectivist; however I know that measurements do obviously not say the last word in audio.
- I prefer searching for emotion inside the recordings; I hate redounding colorations coming from some gears even if they are allowing presumed improved euphony
- to my ears, the most important things are, besides all other qualities, transparency, tonal balance and lack of harshness.
- I listen to many sorts of music/songs, from Gregorian to Asian underground but almost never to symphony and opera; I simply don't like them except sometimes in live events
And don't forget: what follows are my own feelings, related to my own setup and with the tubes in use; as sound's characteristics depiction is inevitably a matter of relativity, I used my SS headamp for direct comparisons and my memory for what I heard from Rudistor RP8, DNA sonett2 and Audiovalve RKV MK2, all gears listened on my hd800 a few months ago; though never heard hugely priced head-amps
Let's go:
 analytic impressions:
- sub-bass: no doubt they are there; nevertheless ideally I feel this range could have a tad more spl; however it's not of great importance as music does rarely contain such frequencies; though I regard this range being remarkable coming from a tube amp
-bass: music stands on a firm base: this range is powerful and solid, well damped; texture is present when recording asks for
- upper bass: same as bass, but slightly forward though not at all boomy nor on the border of boominess. I prefer this than the opposite because it gives some mellowness to music; please read "mellow", not "muddy". So I would say that the global bass-range is at the same time round and solid... may be paradoxical but that's how I feel it
- low-mid to upper-mid: accurate and detailed, rich, fluid, no more no less than perfect to my ears
- low-treble: fully detailed and solid but at the same time surprisingly sweet;  transition with the upper-mid is tonally perfect
- treble: sometimes some sibilance does yet occur on stock hd800 but not in a metallic/artificial way of sound; just a matter of spl at 6kHz. With my mod this range becomes simply accurate, no haze at all but more smoothness, without lowering its sharp-cutting edge
- upper treble: very extended and pure; the little loss in this range with the mod in place is obvious but this drawback is of less importance vs its benefit; however it shows up how transparent Elise is
- dynamic: Elise has largely enough power to listen to the hd800 at high spl levels without any stress
- transients and damping: admirable! even more admirable is that they are equally distributed on the entire bandwidth
- Finally, the noise: what noise? connected to my burnished CDplayer but without running a CD, volume up to the max (5,5 o'clock) the amp is ABSOLUTLY quiet; that's so special!!
 
listening impressions:
- a nice tonal balance with stock hd800 at low, average and high listening levels; the intrinsic lean/rising nature of the hd800's sound is here rather compensated by the strong bass range and the smoothness of the upper range; mod in place the tonal balance becomes quite perfect to my ears on the vast majority of my CD collection whatever the spl listened at
- rendered details and inner details allowing to perfectly hear undertones and slight subtleties. Each sound is related to the other in a beautiful "oneness", i.e. the decay of reverberations is perfect, enhancing their presence and substance; combined to the ultra fast transients and absence of noise, the outline of notes and the verity of tones benefit of course from this feature
- an astonishing absence of harshness, even at high listening levels. Long term listening isn't a problem: I sometimes happen to fall asleep while listening even at comfortable levels. Poor recorded tracks are more listenable than on my SS amp and my modified hd800 on Elise is now able to reproduce all types of music with never ending pleasure
- the wide soundstages and pin point imaging of the hd800 are even enhanced by the accuracy and silence of the Elise; some not very audible notes coming from a deep soundstage are quite perfectly heard and magically pictured
Another proof Elise is a top notch amp: the gap between poor and well recorded CDs is so vast that I needed more of a reasonable time to down on its right listening features
In short: it's stunning to hear such potency, speed and refinement at the same time; in this meaning recorded music gets closer to live music because Elise allows to immerge deeply inside the core of music without any drawback... isn't  what we name "naturalness"?
Elise's price does absolutely not reflect its huge qualities. Ices on the cake: a marvelous sober design, a faultless finish and a great tuning potential through tube rolling. Thanks and congratulations to Feliks team!
 
Side notes:
- standard Sovtek 6H8C drivers sound decent, restrained frequency range but not harsh
- I hoped a nice sound from Nos Jan CLRV 6SN7 WGTA drivers (from C.G.E. _General Electric,_ made  in Canada): well, all the bandwidth is OK but without the refinement of the Sylvanias and sadly a HUGELY sibilant/harsh treble even on modified hd800
- NOS Sylvanias 6080 power tubes would be great tubes if they were as powerful in the sub-bass range and as extended in the upper-treble range as the stock 6as7g Svetlanas; however this less powerful trebles are a good feature for an unmoded hd800 and their global frequency range can be a good match for those listening mainly to acoustic music (jazz, blues ...); in short: a bit too much mid centric tonality.
- NOS Foton drivers tubes: a bit more dynamical then the Sylvanias 6sn7 wgta but restreined soundstages.
- NOS Melz drivers tubes (without holes in the plates): same global sound quality than the Sylvanias 6sn7 wgta but with more powerful sub-bass range, a more linear bass range (no more enhanced high-bass range), a bit more dynamics in the extended mid range and a bit less spl in the treble range. Those are my favorites at time because they mainly add consistency to the hd800 tonality without lowering the refinement of  the 6s7n wgta. Very very nice tubes!

My first venture into tube amplifiers had been with the very budget friendly Little Bear P8, not a bad amplifier for the price but certainly not perfect. The build quality, thermal management and sound left a lot to be desired however, I liked what I heard from the tubes. Doing a lot of reading on tube amplifiers made me form a general idea of what I would want in a tube amplifier in my head.
 
After following the thread about the Elise on Head-Fi and reading all the positive comments from early adopters I decided to take the plunge and order my very own Elise.
 
When the Elise arrived, even before turning it on it was obvious, this is a very different beast compared to the modest P8. The hand-crafted chassis exudes excellence. The way the internal wiring is done, some PCB and some point to point all seems very purposeful. The kind of quality and attention to detail you rarely see in mass produced equipment. 
 
When turned on it was clear, this attention to detail transcended to the sound quality. The detail, speed and ease this amplifiers plays with is uncanny and this was with the already quite good Tung-Sol tubes supplied by Feliks Audio.
 
Listening to the Elise through my Beyerdynamic T1 headphones it was quite noticeable to me that the Elise has not much of a sonic signature all (This is a compliment). On the whole it is very balanced with an ever so slight elevation in bass response and euphonic character. To my ears this is very pleasant. Although the bass seems slightly elevated it is never Woolly, smeared or fuzzy. The presented bass is dry and punchy with a lot of impact. The highs have that silky smoothness that I like in a good tube amplifier.
 
I was going to write about my journey rolling different tubes, some options were very good indeed like the RCA 6SN7 Grey Glass and Sylvana 6AS7G. Instead I would like to take you straight to the tubes that really transformed the Elise for me. The GEC 6AS7G and Lorenz C3g.
 
The GEC and C3gs peaked my interest after reading the comments of thread starter Hypnos1, he was so enthusiastic about these tubes there had to be at least some merit to it.
 
I asked Hypnos1 to make me a set of adapters for me and he kindly replied he would be delighted to do so. He even sourced some C3gs for me. This was ideal since this way he could try them in his adapters and Elise before sending them to me.
 
When these arrived I quickly replaced the National Union 6SN7GT Black Glass with the C3gs... This changed the sound dramatically, there was even more detail to be heard, micro-details became more apparent, Bass became even tighter, more controlled. At first it seemed like there was less bass but that is not the case. The more tightly controlled bass just made it seem that way. The incredibly detailed highs might also seem to offset the balance in their favor. After listening and getting used to this sound signature for a while I actually might prefer this sound.
 
About the same time I managed to find a perfectly matched pair of NIB Round bottom GEC A1834/6AS7Gs for a very decent price. These seem to drive the T1s with even more ease, opening up the soundstage, making it wider and deeper and subtle details have even more emphasis. They really convey the details the C3Gs present very well.
 
If you like crystal clears sound and being able to hear all the details in a recording the Elise with GEC/C3G tubes should be a very good choice for you. My misson searching for the best sounding tubes and amplifier seems to have reached its end. This will be my main headphone- and pre-amplifier for a very long time.
 
If you are interested in this amplifier check out the awesome thread at:
http://www.head-fi.org/t/732875/feliks-audio-elise-previously-6sn7-6as7g-6080-prototype