Pros: neutral, transparent, totally silent, crossfeed, 3gain settings, perfect volume control, usb dac with wide compatibility.
Cons: battery life as dac, a little heavy, its little brother UHA6s mkII is a serious challenger with a very small pricetag.
I've been ranting too much so I've put every time I slipped too far out off topic into quotes. That way you can pass it all and just read a real review if you don't want to be bothered by some #my-life kind of content ^_^.
and there is a short +/- list at the end if you really just want answers.
Obviously we don't all seek an amp for the same reasons so your perfect amp will not be mine:
What I want from a portable amp, by order of priority:
1/ To get under 1ohm impedance output to avoid messing with the sound of my multidriver IEMs.
2/ To get rid of any hiss from my dap!!!
3/ To feel some control over my bass. Bloated bass are not what I usually enjoy(I do like those in games^_^).
4/ To be able to set my volume exactly as I like. On daps I'm often juggling between 2 values hoping for something in between.
5/ I don't mind coloration, but I still expect some level of transparency. If the coloration ends up making the sound harsh or really muddy, then it's a no go.
6/ pass the 10hours mark. Ideally 13h is my own perfect mark for comfort, but 10 to 13hours is ok for 99% of my life. Under 10h is but a nuisance and I won't buy it.
7/ to be reasonably shielded against smartphones.(if I hear my neighboor's phone in a train the amp is useless)
8/ be portable in my everyday uses (yeah I know I'm captain obvious but a lot of attractive amps are too big for me to carry around casually).
9/ If as a bonus I get a little more space for my “headstage”, the more the better. But that is not a real need I have. As long as it's not smaller than the dap alone I'm ok with it.
I never though about getting an amp to get the sound louder, simply because I use portable stuff for portable uses. People with 70db/mw sensitivity cans won't find much interest in my posts, sorry.
The Leckerton was kindly sent for me to demo for a french forum, and I then decided to buy it (should give you a hint about my conclusion ^_^). Right now I have an O2 and the weird cmoy with the third opamp on the ground. And also a Pico amp and a TTVJ slim that 2 members sent me as a loan(thx a bunch).
I've owned or tried quite a few portables amps now, and had a hard time finding some that could work with my 9 points from above(none actually). Just from the level of hiss, half the portables amps on the market are TKOed with a togo! 334 or even a SE535(mostly powerful amps or really cheap stuff).
The Leckerton doesn't solve everything, but ends up crossing most points from my list and that made my day.
Here we go!
The UHA760 is a portable dac/amp, you can get a lot of technical information from the Leckerton website if you want them http://www.leckertonaudio.com/products/uha760/ . And Nick kindly answered to all my extra newbie questions with what I thought to be honesty and confidence, so if you have a specific question don't be shy, he knows what he's talking about.
Basically, the amp section is close to that of the UHA-6S MKII with different gain settings and 2 crossfeed positions. Again you can look for yourself but pretty much everything is done not to be cheap, but to minimize noise and distortion.
The dac part now gets asynchronous, so added with the upsampling to 192khz, jitter maniacs should breath better using usb(coax and optical versions will be available later). The input is still 16/48 for the usb one, I'm guessing other inputs version could get higher resolutions and USB stays as it was for maximum compatibility.
I think I remember project86 telling that Nick was working for Cirrus Logic, so no wonder we get a CS4398 DAC chip in his amps.
The output is under 1 ohm on all 3 gains.
It can charge through USB or you can turn the charging off to save battery life on your source while using it as a DAC.
The op amp I have is the AD8610, you can ask for another one but it's not on a socket so no op amp rolling here.
The volume knob is stiffer and shorter than on the UHA-6, a much appreciated evolution.
So definitely an upgrade to the UHA-6S MKII, but very little change has been done to the sound. if you're on budget, you can give up all the features and still get quality sound from the UHA-6S MKII. I wondered about that choice myself, and decided the upgrade was worth it for my IEMs as I feared some channel imbalance on the 6 when listening quietly, or some accidental increase of the volume while manipulating the amp. Two concerns absent from the 7(also I'm a crossfeed fan).
About crossfeed, for those not familiar with it, it's something that came up as an attempt to mimic the sound of speakers on headphones.
In real life, and with speakers, even if the sound comes only from your left, your right ear still gets some part of it. And the differences in db and timing from both ears will tell you where the sound came from. With headphones when the sound comes only from the left, your right ear gets nothing (or very little and without time delay if the crosstalk level of your gear is high). In any case your brains will not find it natural, basically because it's not.
You can get information about how it works and why it's not simply “putting all left sound delayed on the right” all over the internet so I'll pass on this and go straight to why you might want some crossfeed on headphones.
On recent mastering, they often think about it and avoid placing one instrument or one voice 100% on just one side. But still most masterings are done with speakers and therefore done to be listened with speakers. Also most old recordings don't give their best on headphones.
Crossfeed helps for that.
But as adding crossfeed tends to logically reduce the “headstage” in width(think about the sound when it's in mono, up front but no width, crossfeed will make a tiny percentage of this change in space), some people might prefer to listen without crossfeed. Anyway the choice is available here, with or without, I find the sound to be very good and clean.
As an example the last titles where I found the crossfeed to be an improvement: Prince – Thunder. With Prince and the huge drum impact on the extreme left the entire song, it got annoying very fast. With crossfeed I pushed everybody slightly more in front of me. Still on the left for prince, but more as a “I can see you” left, instead of “that weird looking guy is singing into my ear, I'm not comfortable with a man's mouth so close to my ear” kinda of presentation ^_^.
Later I got Stevie Wonder (my personal god) singing “look around”. This time Stevie was on my right the entire song... On speaker the song is simple, yet one I love, on cans it's the kind of songs I would remove from my dap. Some crossfeed made it enjoyable again for me. And I can think of a lot more, like most of Gainsbourg's songs, or a lot of the Beatles where the recordings were clearly intended for speakers at a time when Dr Dre's minions didn't yet roam the earth by the millions.
I find the first crossfeed level to be very discrete and to work most of the times for all kind of recordings without reducing the headstage too noticeably. You could use that one and just forget about it. The second level is what I'm used to for crossfeed, and what I think is closer to speaker imaging. Anyway the choice is mine and I very much welcome this on portable gear in a non dsp implementation.
With the HF5 I always find the soundstage to lack volume (instruments are on some kind of line on the ears axismost of the time). The crossfeed felt more pleasing to me, creating some sens of depth by just moving some bass a little more before me.
Another effect of crossfeed is that the listening is less tiring. Often less impressive too, but my brains clearly spend less time wondering what's happening, it's not night and day and will depend on what you're listening to. My long listening sessions are now with crossfeed.
All I'm describing is more or less subtle, don't expect a revolution in your head, the point of crossfeed is not to be too noticeable, it's not a surround DSP.
Laptop to odac+o2 (gain 1X) vs laptop to UHA760 (gain 0db and tried again at gain -12db with the same observations)
I've tried both extensively with everything I had: IE80, JH13, Parterre, 334, HF5, HD650, and a few crappy IEMs and earbuds (the best of those being the 30$ xba-c10).
They are so close in every possible ways, just go read something about the O2/Odac and you have it. At first I had noticed a lot of differences (and trying hard to get some as in my head there was no way the Leckerton could be equal to my beloved O2.
But when I went serious for the review and started to use a switch and do some better (still by ear) level matching, all the differences just faded away. I honestly don't think I could accurately tell one from another with my IEMs in a blind test. I feel like there is a difference when switch, but I just need to switch 4 or 5 times thinking about something else, and I would fail to tell which one I'm actually listening to.
And pretty much the same thing when using just the amp section I felt like the O2 had maybe a tad more extension in the sub bass(or at least was a little louder in that region) and a very tiny bit more trebles(yet lusher sounding), but I wouldn't bet my money on those observations as this time I had to unplug the LOD to switch, and that action and delay are often enough to mess things up in my head. I tried to be clever using some jack-to-double jack plug on one end and my switch on the other, but I ended up with some slight noise into the O2(the Leckerton didn't care at all) so I resolved to plugging/unplugging for amp only comparison.
No matter how much time I spent, my thoughts were that they were both very close and very neutral/transparent. I felt that my hd650 could do a little better on the O2 and this started my suspicions about the sub bass. So very slight roll off, or maybe a little problem with sub bass control? I don't really know and going back to dac+amp for instant switching I couldn't confirm anything.
I honestly enjoy the hd650 on the UHA760. There is that lingering feeling from past memories telling me that the hd650 can do better, as every time I plugged it into a powerhouse it seemed to upscale with the source. But that's already a special headphone and not a portable one. I believe anything made for portable gear will be more than well fed, powered by this amp.
So what differences can I talk about?
Well the size would be a good start, to me the more obvious reason to buy one or the other (or both like I did) is that the knob and gain on the O2 aren't ideal for sensitive IEMs. It's too loud or you have to struggle to avoid channel imbalance. As much as I love the O2 with my JH13 when, by chance, I can get the desired volume without issue, it's still much nicer to use the O2 with headphones.
The Leckerton has digital volume control and 12/0/-12db gain switch that makes it ideal for IEMs. But very low sensitivity headphones might not go loud enough.
So no this is not the all in one wonder everybody keep asking for, it might not drive your orthodynamic loud enough. But it will drive anything that a normal human being would call portable. [troll ON]It's almost as if Nick had decided to make a portable amp for portable gears... Those amp guys have the strangest ideas. He should know by now that the first question on headfi for a portable amp is “how does it drive the LCD2?”[/troll OFF]
The maxed out volume at high gain got badly distorted when I tried(cable with volume control added between the amp and my hd650 so it obviously added a lot of impedance to the headphone from the amp perspective). Anyway it seems like you can't push the UHA760 to the limit at max gain. The max output on the website being at 1%THD, the given specs are obviously the usable ones and you can trust them, then the amp still have power under it's foot, but the distortion gets audible. I was on mid gain with the hd650 and it gets LOUD, so I wouldn't worry about power on anything portable.
So here you have it, this amp is pretty neutral and uncolored. Something a lot of people actually don't like as they expect an amp to add some kind of wow effect and a lot of bass. Again we all have our tastes and ways to achieve our desired sound. I find it easier to get a dap I enjoy using, a neutral amp and then find the headphone of my dreams within the amp's drivable range. But you can chose to find the amp for your phone instead, in which case a neutral amp might not be what you want. I just go for the pragmatic/lazy way.
I know a lot of people find the O2 to be a boring amp. In a way I agree with them as it doesn't bring the excitement of a dynamic sounding signature, it's doesn't make the sound tighter, or warmer, doesn't add grain like a tube can … But it never was the purpose of a neutral amp, the idea of a wire with gain does fit the O2 very well. Anyway, clearly what you thought of the O2's sound (good or bad) will apply here with the Leckerton as strangely enough, a clean neutral amp does sound close to another clean neutral amp (mind blown!).
Absolute silence, you're lost in space listening to your music and Sandra Bullock actually stopped talking. Grumpy cat is impressed.
For reference, I find most sources to be hissing. The dx50, all Sony daps I've owned, all hisound daps, and surprisingly even most amps. Using super sensitive IEMs like the 334 and listening at ludicrously low volume levels at home, gives me an open window on noise and I hate it. Just that perfectly silent background made me fall for the UHA760
Smartphones arrrrghhhhhhhhhh...... :
You don't want to stick an active phone to it. It's noisy until 15 or 20cm away depending on the orientation of the amp and almost inaudible at 40cm from my phone in communication (and trying hard to get some noise). The most sensitive part being where the cables are as usual.
Compared to the amps I had around, it was actually the best result :'(. I remember the Pico slim to be almost completely quiet, while with my RSA Protector I could track the guy with a phone 3meters away just by ear. The Pico(not slim) was sensitive around the same distances as the UHA760, but was making picked up noise much louder and from all directions.
I tried with fiio LO cable that are kind of prone to help picking EMI, I used it to be fair with my memories of older amps that I did use with FIIO's lods. The ground seem to surrounds entirely the left and right wires, I believe braided cables would deal with EMI better than this.
Doing this kind of exercise I learned a lot about the few tracks I looped and discovered a lot of new little details just because I was paying mighty attention instead of singing with the guy. That might be a good way to get the best out of our sound, to actually pay attention instead of upgrading every 3weeks.
I’ve learned a little about the amps and tend mostly to favor external amps to any dap's HO alone. There is almost always something to gain from an external amp(sad pun is sad).
On the other hand, I fail to see much difference between a usb dac and another usb dac when looking at portable stuff(home dacs are another story). They all do nicely and sound very close without ever giving a real thrill. It's nice to have an integrated dac so I can actually use my laptop as a source, but that's about it. If I like the sound of my dap, I will use its integrated dac instead of the one in a portable amp.
Of course if you dislike the sound of the dac inside your dap it's a different story. But then simple me would get another dap.
Anyway as I said above nick has done a good job setting the dac and amp part of the UHA760 so that the sound would be neutral and clean (by ear, I have no fancy tool to check my observations).
to give an idea about the amp size:
Some other amps:
the TTVJ slim was OUT from the start because of some serious hiss in my IEMs. Also it's not a neutral amp. Despite real audio qualities, a very pleasant sound signature placing voices as the main event, this is clearly not an amp for sensitive IEMs. It's more some kind of warm tube amp sound made into a very slim box.
The fredfred cmoy is OUT mainly because the sound signature is going down too much, and I found the instruments to lack in texture. A channel imbalance coming pretty soon at low volume was the last needed push out of that review.
The O2 has probably the best overall result. Big soundstage, no hissing, a neutral sound and a lot of power. In sound/$ it's my all time champion against anything. Sadly its volume knob doesn't go that well with vey sensitive IEMs even with the gain at 1X. And of course the size is well above what I would consider portable.
The Pico(no slim) to me, is inside the neutral amp team, the one with the fun sound in it. The sound isn't really colored, it's a very good amp doing its job in a very small box. There is a little something on bass and trebles where I felt like they had slightly more crispness than with the O2 or UHA760.
Based only on sound I might have taken this Pico, but the form factor despite being small, isn't really practical once stuck on a DAP(maybe with a fuze or something small). Also I got some troubles with the analog volume knob. Normal volume listening is no problem, but a calm listening with my IEMs was impossible due to channel imbalance on the lower 1/3 of the knob.
The Pico slim is even more fun, but this time to the point that it's not really neutral anymore. Bass and trebles have a clear boost to my ears(the pico no slim is overall a superior amp). Great digital control of the volume, an incredible size, an amazing battery life, this boy deserves success as an IEM amp. Its limitations are mainly that it should be used only with IEMs and maybe a few very efficient portable headphones. I sold mine because I felt its soundstage/headstage was really lacking in depth. Give me a Pico slim with crossfeed and I might never look at another amp for IEMs.
+natural sound very close to what I call neutral.
+Volume control is simply the best I've ever had for my sensitive IEMs. Hard to turn knob+digital volume control+ gain swith= perfect control.
+Crossfeed (2different settings).
+Light turns red when battery gets low instead of dying on you without notice, and will really go down in the next hour.
+Usb charging can be turned off if used as a DAC with tablet or laptop to save battery.
+Absolutely no hiss on any IEM. I mean it!
-You can find sharper and more resolving, or at least with more power if it's what you like/need(but I doubt you'll have it with the same neutral sound).
-Heavier than it looks.
-EMI shielding isn't great in a 20cm radius so you'll have to use airplane mod to pair it with your phone.
-Batterie life around 12h as an amp and around 5 or 6h as a dac/amp(with usb charging OFF). The UHA6S mkII does a lot better for less money.
It solves almost every single problems I ever had with IEMs. If the EMI shielding was a little better I would call it the perfect IEM amp. Far above my second favorite, the pico slim, that still has its size and battery life to be proud of.
I can obviously think of “better” sounding or at least more powerful amps if I forget about hissing, channel imbalance and size. But the ease of use of the Leckerton really made me forget the extra 5% of sound happiness I could get elsewhere. As I said to Nick, this amp does make a lot of sense to me and answered my “nomad with IEM” difficult needs.
No need to deal with some “I can't pass the first ¼ of the knob because it's too loud” nonsense. No “I have to listen louder because lower has channel imbalance” facepalm. If you're like me a heavy IEM user, you know what I'm talking about and are probably a little fed up with it. You can always find a dap with volume control on the line out, but technically it means getting the noise floor of the dap up. Not always a problem but in this world of perfection seekers, why not avoid it?
All this to say that good volume control on the amp matters a lot more to me as an audionerd than any dsd, or frozen diamond cables. And Nick did exactly what I needed on the UHA760. Between the 3 gain settings, the precise digital control and the harder to turn knob, the Leckerton is really a pleasure and a secure tool to use with IEMs. If you want to know portable quality with a minimum of drawbacks, I believe this amp is a serious solution.