[ThanatosVI]

EKSONIC AERAS REVIEW

Thanks to the kind generosity of @Kerry , the proprietor of Eksonic, I was able to home demo the Eksonic Aeras estat amp for the past month. I was able to listen fairly extensively to the Aeras in comparison to my NAD/iESL setup, with both my recently purchased STAX SR-X9000, as well as with the STAX SR-009S, which I had purchased a couple of months ago as a stopgap until my X9K arrived.

To facilitate easy comparisons between the Aeras and the iESL, I simultaneously used both the RCA and XLR outputs from my reference DAC, the EMM Labs DA2 V2. I also inserted my Benchmark DAC3 into the chain before the Aeras to convert RCA (DAC output) to XLR (Aeras input), as well as to provide remote control of volume and muting. The DAC3 is a middling DAC in my opinion, but its preamp section is quite superb and very transparent based on critical A/B testing I've done in the past. That said, the Aeras arguably would have sounded even better with a direct XLR connection from my EMM Labs DAC. For completeness, here are the respective chains used in my listening sessions:

DA2 V2 DAC (XLR) ---> Audio Research Ref 6SE Preamp (XLR) ---> NAD M22 V2 ---> iFi iESL Energizer ---> Estat headphone

DA2 V2 DAC (RCA) ---> Benchmark DAC3 (RCA analog in, XLR out) ---> Eksonic Aeras ---> Estat headphone

=========

Before discussing sonic impressions, herewith a brief digression on the ergonomics of the Aeras amplifier. The Aeras represents trickle-down technology from the universally highly acclaimed Eksonic DIY T2 estat amp, in a much smaller form factor and at roughly half the cost. The Aeras features a single (rear) XLR input and a single STAX Pro-Bias headphone jack. There is also a large volume knob and a power switch with a ring LED on the front panel. The volume is not controllable remotely. After being switched ON, the Aeras enters standby (muted) mode, indicated by the power LED flashing, as well as a handful of red LEDs illuminating near the front of the complement of four (4) 6S4A tubes socketed atop the amp. After perhaps 30-45 seconds (I never timed it), the Aeras comes out of standby (and unmutes), indicated by the power LED transitioning from flashing to solid ON, as well as another dozen or so red LEDs illuminating throughout the region of the tube sockets. Operation was extremely straightforward, and I encountered no glitches whatsoever during my month of use.

Aesthetics are subjective, but I find the Aeras to be a very attractive piece of gear. There is an elegance, not to mention tremendous practicality, in its compact form factor. Fit and finish are exceptional. There are no sharp edges on the heat sinks or elsewhere, and the matte finish to the metalwork is beautiful. The Aeras would be a top choice for an estat amp to fit on a desk or bedside table, or to take on the road.

I should note that the Aeras operates in class A and gets very warm. Several seasoned estat folks have pointed out that this is true of virtually all the well-known estat amps, whether tube or solid state. The Aeras may be slightly disadvantaged in dissipating heat due to its smaller form factor. Even though we live near the coast and don't have A/C in our house, the heat from the Aeras didn't noticeably affect ambient room temperature. My only minor niggle was that the front panel and volume knob also got rather warm to the touch after a period of continuous operation. I did mention this to Kerry, and he told me it may be possible to improve thermal isolation of the volume knob, but probably not the front panel. Since I was controlling volume remotely, I really only noticed this when plugging/unplugging a headphone, and it wouldn't be a deal-breaker for me in any case.

Sonic Impressions

The Aeras arrived prior to the STAX SR-X9000, so my initial evaluation was done using the STAX SR-009S (and briefly, the Hifiman Shangri-la Junior). I'd had the 009S for maybe a week prior to the arrival of the Aeras, so I'd formed an initial impression of the headphone driven from my iESL. Generally, I really liked what I was hearing from that combo. Bass was definitely elevated compared to my Shang Junior, and the timbre was more realistic than I'd remembered it from other auditions, typically on the BHSE. The technical proficiency of the 009S is high, if not quite state-of-the-art, and it exhibits most of the virtues of the better estats, while committing no overt sins of any real consequence. I found the tuning of the 009S through the NAD/iESL combo to work well for virtually all genres of music.

So what were the differences when moving the 009S over to the Aeras? In a nutshell, the Aeras served up an increase in treble energy. The subjective results of that were better depth and layering of the soundstage (with maybe a slight decrease in width), more shimmer and air around cymbals, and an increased vibrancy/glow to the music overall. I hadn't felt like something was missing with the iESL chain, but once I moved to the Aeras, music just sounded more energized and lifelike. The only downside of the Aeras/009S pairing was that the occasional recording exhibited a bit of heat or glare in the treble. I'd sometimes noticed this before with the BHSE/009S pairing, and I'd mostly attribute it to the 009S, as it was never an issue with the Aeras later driving the X9K. It's also highly likely the issue could be addressed via EQ, but I didn't bother to experiment with it since I knew the X9K was on the way at that point.

After the X9K arrived, I really didn't listen to the 009S anymore. As expected, the X9K also exhibited a bit more treble energy when driven by the Aeras vs. the NAD/iESL. Subjectively, however, the differences between the amps weren't as prominent when listening to the X9K. There was still an increase in soundstage depth/layering with the Aeras, and a bit more shimmer/air around cymbals, but the baseline established by the NAD/iESL/X9K combo was so excellent that the improvements from the Aeras seemed more incremental than they had with the 009S. I still think a majority of listeners would prefer the Aeras (as do I, in general), especially those who find the X9K a tad reticent in the treble region. There were occasions where I felt the iESL chain had a bit tighter grip on the bass than did the Aeras, but it was close enough that I couldn't say for sure. I will also note that when I listened to either amp for a period without switching, my ears seemed to adapt, and I was able to just normalize and enjoy whatever I was hearing at the moment. One takeaway from this experience was that the NAD/iESL is not a second rate option for driving estats by any measure. It may not be at the top of the mountain, but it's within shouting distance. Of course, I've only heard the Eksonic DIY T2 briefly at CanJam, and not with the X9K, so the gap may in fact be much wider than I'm imagining.

Bottom line: I would recommend the Eksonic Aeras without reservation! Paired with the STAX SR-X9000, the sound quality was nothing short of spectacular. The Aeras also sounded fantastic with the STAX SR-009S. The only headphone which I preferred driven by the iESL was the Hifiman Shangri-la Junior. It's a rather bright estat to begin with, and it had better synergy with the iESL chain to my ears.

As always, one listener's subjective opinion. YMMV.

Thx for the review, seems like I'd personally prefer the iESL here

 

[BassicScience]

Thanks for the detailed write-up. Like you I'm utilising an energizer to run my STAX (009) with my existing pre and power (see sig). While not as rarified as your chain I figured taking advantage of existing amps would (hopefully) get me close to a high quality dedicated electrostatic amp that would be better than my weak STAX SRM-007tII.

Reading your impressions it seems that while there are advantages in buying a high-quality dedicated 'stats amp the marginal gains are not worth the outlay vs sticking with the energizer.

You're welcome. Glad you got something out of it.

There are far too many variables in play to quantify how much "marginal" sonic gain a dedicated estat amp will provide in any given system/user context. In addition, how much that marginal gain will be worth (subjectively, and in terms of cost) to a given individual is equally nebulous. I think the main takeaway for me was that energizers can (under the right circumstances) go head-to-head with high-end estat amps, and not be remotely embarrassed.

 

[BassicScience]

Thx for the review, seems like I'd personally prefer the iESL here

You're welcome. Bear in mind that the sonic results from the iESL are certainly dependent on the amp driving it. I haven't had a chance (or the inclination, really) to experiment with other amps, but will update this thread if I ever do.

 

[number1sixerfan]

Really enjoyed reading this review. Had very similar thoughts with my time with the same demo unit. Really amazing for what it packs into such a small form factor. I do also really like the flexibility of what the iESL provides, so it's cool to see that it sounds like it performs really solid in comparison to it.

 

[BassicScience]

In regards to my recent review of the Eksonic Aeras amp in this thread, I received the following message today from @Kerry of Eksonic, reprinted in its entirety here, as well as appended to the review itself:

I got the Aeras back yesterday. It turns out that the heatsinks on it were from an earlier version and they run about 8-10 degrees F hotter than the current production. That explains why they felt hot to you - because they were. I didn't remember that the one I sent to @number1sixerfan had the older heatsinks. The electronics are the same in both.

[Editor's NOTE: My Aeras demo unit had originally been sent to @number1sixerfan several months ago, and I received it directly from him.]

The photo below shows the difference. I spent a bunch of time designing the new front heat sinks (right) vs the earlier off-the-shelf heat sinks (left). The larger spacing really helped.

You can also see that the finish is a bit different too. The newer one is a semi-gloss anodized (top/bottom/back) vs the flat anodized that you had.

 

[all2ofme]

So lovely. Kerry’s work is just

The attention to detail makes waiting for my T2 even harder!

 

[hifixman]

Submit fi electrostatic systems Shootout: Sennheiser HE-1 VS Hifiman ShangriLa SR

( Sound demo starts from 2:40)

https://b23.tv/8N8uyT0

There are three demos for comparison: ShangriLa SR recorded by 150K USD recording setup, and ShangriLa SR and HE-1 record by a 350 USD 3audio

 

[orrman]

Hi everyone, new to the estats world and had just a few minutes with the X9K but that was enough to make me want to listen to it for more time. If anyone in the NJ area (07670) wants to discuss a potential loan/trade I'd be happy to try and get that done. My gear is in my signature. Thanks!

 

[BassicScience]

STAXus Interruptus or: A Funny Thing Happened on the Road to E-Stat Nirvana

I recently sold my STAX X9000 in response to a WTB post on its dedicated thread. I wasn't actively shopping it, or even thinking about doing so, but I've started selling off some assets to raise cash for major improvements (new roof, solar installation) to our house next year. That, coupled with the reality that my Susvara was getting a majority of my head time lately, resulted in the decision to sell the X9000 when the opportunity arose. Here's the (somewhat long-winded) background in case anyone's interested:

My wife and I went on a cruise during the latter half of September. Before we left, I'd owned the X9000 for a couple of months, and it had supplanted the Susvara as my "go to" headphone for nightly listening sessions. I was smitten with its technical prowess and capacious soundstage. I had already ascertained that the Susvara was the superior headphone for most rock music, but over the last year I'd been more focused on jazz and (experimental) electronica, with some classical and vocal-centric music also in the mix, all of which played to the X9000's strengths.

In my ideal world, I would have a single reference headphone that would excel with any type of music. Accurate timbre (fidelity) is my key criterion, followed by bass extension/linearity and soundstaging. I seek the most convincing illusion that I'm listening to live music, or at least full-range speakers. Prior to my entrance into the realm of estats, the Susvara was that headphone, but the even greater resolution of estats seduced me into thinking/hoping there might be an even higher peak attainable. When I ordered the X9000, I thought there was a reasonable chance it would make the Susvara redundant. Within a few days of its arrival, though, I realized the Susvara was still essential for rock. Nonetheless, the X9000 was just capable enough there that, along with its glorious staging/imaging prowess and resolution, I quickly anointed it the new overall #1.

So after a couple of months of owning the X9000, we leave for the cruise, and the only headphone I pack is my SONY WH1000XM4 (noise-canceling). I want to travel light and plan on spending a lot of time lounging by the ship's pool anyway. My Galaxy S10 phone will be my (Bluetooth) DAP. In spite of my love of high-end audio, I'm not a snob about it, and the sound of the SONY is perfectly acceptable for recreational listening. One day as we sailed along, I was reading Head-Fi for entertainment, and the remaster of Pink Floyd's Animals record became a topic. I don't listen to Floyd much anymore, but I've always really liked that album, and decided to check out the remaster. Even on the SONY cans, the increase in clarity over the original master was obvious, and beneficial to the enjoyment of the record, I thought. From there, I decided to listen to Floyd's previous album, Wish You Were Here, my favorite of their post-Syd Barrett oeuvre, and perhaps ironically, inspired by Barrett. Maybe it was just the circumstances (sipping a drink by the pool on a Mediterranean cruise), but even on mediocre headphones, the album had never moved me as much as on that day. Gilmore's guitar playing on Shine On is so phenomenal in terms of its emotive power and lyricism, and at that moment it just made me feel like a teenager again, connecting with it for the first time. And when the album was over, I decided it'd be the very first thing I listened to when I got home... on the X9000! Unimaginable sonic glory awaited, surely.

After a looooong day of flying back to California from Tunisia, I crashed immediately, and was still pretty jet-lagged the following day. Nonetheless, I'd been looking forward to hearing Shine On since that day at the pool, so after unpacking, the time was at hand. I let the system (mostly tube preamp) warm up for about fifteen minutes, donned the X9000, and hit play. The track starts very softly with some multi-tracked synths establishing a spacey ambience. Just after the 2-minute mark, the guitar enters with some plaintive, plucked phrases immediately evoking a longing and pathos that always cuts through my core........... except.......... at that moment I was feeling nothing. OK, give it a little time, maybe my hearing/brain is off-kilter from the previous day's arduous journey. At 3:55, Gilmore introduces a 4-note motif. The motif is repeated several times, and then the bass and drums crash in at the 4:30 mark to provide propulsion and rhythmic counterpoint as Gilmore solos in and out masterfully for the next several minutes. Roger Waters' loping, contrapuntal bass is the foundation of the track from that point on, but lack of impact on the X9000 stripped it of its usual emotional gravitas. I was hearing all of the notes with perfect clarity, but I felt like a detached, casual observer of a recording. There was a lack of drama and immediacy.

It was time for a sanity check. I switched over to the Susvara, and played the track again from the beginning. The first thing I noticed was more of a feeling of presence. The synthesizers had gained tangibility. Along with this came an immediate sensation of emotional connectedness that had been missing for me with the X9000. When the guitar entered, its bite had been restored, and with it, the ability to engage my emotions. Likewise, when the rhythm section crashed in, it was properly climactic and weighty. I listened to the rest of the album, as I had been anticipating for many days, and realized that I had come home in more ways than one. While I had already come to the conclusion that the Susvara was superior to the X9000 for all types of rock, the size of the chasm was now laid bare.

I listened to a lot more music that day, of various genres, alternating between the X9000 and Susvara. The perception that music was more palpable through the Susvara was consistent no matter what I listened to. I realized that I value this much more than the X9000's slight advantages in resolution and soundstaging. And with that realization, a short love affair was over, and a much longer one was resumed.

To be continued...

 

[mtoc]

your situation is very rare, stax flip flop is not too common, susvara flipped at the end, can say almost like political flipping, with drama

 

[eee1111]

You gonna regret.

Maybe you got one of the rare duds that are out in the wild that are lifeless. In this topic there are comparisons of 2 that sounded different than each other

Or just different ears

 

[all2ofme]

Great write-up. Good that it was such a clear decision, too!

I’m hoping I don’t end up in the same spot (since I sold my Susvara), but I don’t doubt for a moment that the Susvara will do some things better than the X9000. I’m hoping my other headphones (Phi TC, Empy, XC — all through a CFA3) help in those cases.

 

[eskamobob1]

Rofl. People are so defensive here. I agree with the impressions. Imo, basicaly all estats have a tendency twoarda lack of presence that make the chain so so much more important and difficult to realy nail down. There isn't anything wrong with going "I've got an amazing chain that makes sus make me rap my foot. I have no desire in struggling to see if I can do the same for a can that doesn't do that"

 

[Chefguru]

STAXus Interruptus or: A Funny Thing Happened on the Road to E-Stat Nirvana

I recently sold my STAX X9000 in response to a WTB post on its dedicated thread. I wasn't actively shopping it, or even thinking about doing so, but I've started selling off some assets to raise cash for major improvements (new roof, solar installation) to our house next year. That, coupled with the reality that my Susvara was getting a majority of my head time lately, resulted in the decision to sell the X9000 when the opportunity arose. Here's the (somewhat long-winded) background in case anyone's interested:

My wife and I went on a cruise during the latter half of September. Before we left, I'd owned the X9000 for a couple of months, and it had supplanted the Susvara as my "go to" headphone for nightly listening sessions. I was smitten with its technical prowess and capacious soundstage. I had already ascertained that the Susvara was the superior headphone for most rock music, but over the last year I'd been more focused on jazz and (experimental) electronica, with some classical and vocal-centric music also in the mix, all of which played to the X9000's strengths.

In my ideal world, I would have a single reference headphone that would excel with any type of music. Accurate timbre (fidelity) is my key criterion, followed by bass extension/linearity and soundstaging. I seek the most convincing illusion that I'm listening to live music, or at least full-range speakers. Prior to my entrance into the realm of estats, the Susvara was that headphone, but the even greater resolution of estats seduced me into thinking/hoping there might be an even higher peak attainable. When I ordered the X9000, I thought there was a reasonable chance it would make the Susvara redundant. Within a few days of its arrival, though, I realized the Susvara was still essential for rock. Nonetheless, the X9000 was just capable enough there that, along with its glorious staging/imaging prowess and resolution, I quickly anointed it the new overall #1.

So after a couple of months of owning the X9000, we leave for the cruise, and the only headphone I pack is my SONY WH1000XM4 (noise-canceling). I want to travel light and plan on spending a lot of time lounging by the ship's pool anyway. My Galaxy S10 phone will be my (Bluetooth) DAP. In spite of my love of high-end audio, I'm not a snob about it, and the sound of the SONY is perfectly acceptable for recreational listening. One day as we sailed along, I was reading Head-Fi for entertainment, and the remaster of Pink Floyd's Animals record became a topic. I don't listen to Floyd much anymore, but I've always really liked that album, and decided to check out the remaster. Even on the SONY cans, the increase in clarity over the original master was obvious, and beneficial to the enjoyment of the record, I thought. From there, I decided to listen to Floyd's previous album, Wish You Were Here, my favorite of their post-Syd Barrett oeuvre, and perhaps ironically, inspired by Barrett. Maybe it was just the circumstances (sipping a drink by the pool on a Mediterranean cruise), but even on mediocre headphones, the album had never moved me as much as on that day. Gilmore's guitar playing on Shine On is so phenomenal in terms of its emotive power and lyricism, and at that moment it just made me feel like a teenager again, connecting with it for the first time. And when the album was over, I decided it'd be the very first thing I listened to when I got home... on the X9000! Unimaginable sonic glory awaited, surely.

After a looooong day of flying back to California from Tunisia, I crashed immediately, and was still pretty jet-lagged the following day. Nonetheless, I'd been looking forward to hearing Shine On since that day at the pool, so after unpacking, the time was at hand. I let the system (mostly tube preamp) warm up for about fifteen minutes, donned the X9000, and hit play. The track starts very softly with some multi-tracked synths establishing a spacey ambience. Just after the 2-minute mark, the guitar enters with some plaintive, plucked phrases immediately evoking a longing and pathos that always cuts through my core........... except.......... at that moment I was feeling nothing. OK, give it a little time, maybe my hearing/brain is off-kilter from the previous day's arduous journey. At 3:55, Gilmore introduces a 4-note motif. The motif is repeated several times, and then the bass and drums crash in at the 4:30 mark to provide propulsion and rhythmic counterpoint as Gilmore solos in and out masterfully for the next several minutes. Roger Waters' loping, contrapuntal bass is the foundation of the track from that point on, but lack of impact on the X9000 stripped it of its usual emotional gravitas. I was hearing all of the notes with perfect clarity, but I felt like a detached, casual observer of a recording. There was a lack of drama and immediacy.

It was time for a sanity check. I switched over to the Susvara, and played the track again from the beginning. The first thing I noticed was more of a feeling of presence. The synthesizers had gained tangibility. Along with this came an immediate sensation of emotional connectedness that had been missing for me with the X9000. When the guitar entered, its bite had been restored, and with it, the ability to engage my emotions. Likewise, when the rhythm section crashed in, it was properly climactic and weighty. I listened to the rest of the album, as I had been anticipating for many days, and realized that I had come home in more ways than one. While I had already come to the conclusion that the Susvara was superior to the X9000 for all types of rock, the size of the chasm was now laid bare.

I listened to a lot more music that day, of various genres, alternating between the X9000 and Susvara. The perception that music was more palpable through the Susvara was consistent no matter what I listened to. I realized that I value this much more than the X9000's slight advantages in resolution and soundstaging. And with that realization, a short love affair was over, and a much longer one was resumed.

To be continued...

I talked about this a bit in the x9000 thread - but with different tracks.
The x9000 has less volume change between quiet and loud passages, even in comparison to other estats (especially the sr-omega). This does not work well with older recordings, even remastered ones. The who's Bab o'riley is unlistenable for me on the x9000.
However, on newer mastered recordings, where the volume is already intentionally adjusted for dynamics (basically anything newly produced after 2000), the X9000's technical advantages make it an unbeatable headphone imo. The observation is basically that the x9000 is not so much genre sensitive as it is time-period sensitive lol.

 

[number1sixerfan]

Rofl. People are so defensive here. I agree with the impressions. Imo, basicaly all estats have a tendency twoarda lack of presence that make the chain so so much more important and difficult to realy nail down. There isn't anything wrong with going "I've got an amazing chain that makes sus make me rap my foot. I have no desire in struggling to see if I can do the same for a can that doesn't do that"

Agree, we should be able to accept that everything isn't everyone's cup of tea and even though we may love something, there are always imperfections with it. Similar to Chefguru, I also shared similar thoughts in the x9000's thread about its "softness". We're all describing it a bit different, but it points to similar and consistent themes, which is ok.

For me, the x9000 could never be my ONLY driver for these reasons, but it's technically amazing and I enjoy the presentation at times as a complement to the others that I prefer as more of a standard.