I'd like to tell you that I had read a lot of excellent reviews about this thing and was biased in favor of it. Greatly, in fact. Somebody who I really respect recommended it to me and the review I'm writing wasn't even imaginable when I bought this and switched it on.
Setups Compared
iPad Mini Retina -> Superlux HA3D -> HD 650
Asus STX -> Superlux HA3D -> HD 650 / 598
Asus E1 Muses -> Garage1217.com Project Ember 1.0 -> HD 650
Setups From Memory
Asus STX -> Garage1217.com Project Ember 1.0 -> HD 650
Sounds close to the E1 Muses / Garage1217 pairing. Maybe a bit different. But not that far. Both are pretty good. But again, they are in different price brackets. And honestly I don't believe even an iPhone DAC is a limitation.
iPad Mini Retina -> FiiO E12 -> HD 650
Asus STX -> HD 650
iPad Mini Retina -> HD 650
MacBook Air Early 2014 -> HD 650
BRIEF
Superlux HA3D disappoints. However, It trounces the Fiio E12 in terms of transparency, resolution, clarity and details. But it still loses out to the Fiio E12 in producing a smooth and non-rough sound.
Between the Fiio E12 and Superlux, it comes down to preference. However, the Superlux is technically superior and far more powerful, in fact way too powerful.
Actually, details are excellent. It may even compete if not beat the Ember in detailing, at least partially, not sure though. Didn't test long enough. However, I would any day take the STX amp over the Superlux as both are neutral and transparent and detailed, but the STX is smoother, less rough and more enjoyable.
The Superlux, It has enough gain and does go very very loud. So loud that it is infact a con as there is nearly no travel available with the volume pot.
IMPRESSIONS
There is a certain roughness to the sound. There isn't any grain in the conventional manner. But the sound is a little rough and coarse. It doesn't have the smoothness of my AVI speakers or the other setups I have ever heard.
Even my hybrid tube amp sounds cleaner and smoother in comparison. The sound signature isn't that different but my other amps are cleaner and much more refined. Even the Asus STX jack. The Fiio E12 of course isn't better than the Superlux except for the fact that it is smooth, but not very clean either, and definitely not more refined than the Superlux. Not sure which is more refined between the Fiio and Superlux, didn't test the Fiio again.
There is no distorting in the form of crackling but it just doesn't seem to be able play the HD 650 with any smoothness or refinement. I say this primarily because of the certain roughness I heard. The bass slam and stuff is just fine.
HA3D has a completely black background. And that is one thing that goes in its favor.
However, with the exception of a MacBook Air or iPad Mini Retina not being loud enough to power a HD 650, I even preferred those setups to the HA3D if all you want is very soft volume levels.
And yes I tried several hours of burn in on and off my ears. I tried to get used to it. I took breaks and came back. Nothing helped.
I even tried the HD 598 which sounded absurd out of these, perhaps due to an impedance mismatch issue. Since the Superlux has a 200 ohm headphone out impedance.
Mids
The midrange is a little recessed. Not too bad. But definitely recessed. And it isn't involving. It is clinical. And I say that as a bad thing. I have tried the headphone jack of Asus STX and FiiO E12, neither is anywhere near as loud, but both are better in this regard. Either is more engaging. And even AVI speakers are far better than this in this regard. In fact, I like clinical and analytical, but this isn't that good compared to other setups I have, trust me!
The Fiio is in the same league as the Superlux actually, with both having their strengths and weaknesses. The STX is better than both.
Highs
The highs are slightly harsh. And they don't sound that natural. Just rough. Again, I know I am emphasizing this, and I believe I may be overdoing it. Because in this price bracket it may be very good actually, but I have no idea whether that is or isn't so. The roughness isn't that over emphasized, but that is one of the only drawbacks this HA has.
Bass
The bass is tight and good. No major issues here.
Soundstage
The sound stage isn't as good as Ember, but no major issues here either.
ON THE PLUS SIDE
The biggest plus is it manages to totally unveil the HD 650. Maybe better than most/all setups I have heard, by a small but audible margin. However, at the same time it does make it sound rough, coarse and sorta unclean and very slightly harsh, which is absolutely unlike the HD 650 is meant to behave.
It is built like a tank. And I mean it when I say it.
It isn't very heavy. It is portable, not pocketable but transportable. It runs on 2 AA batteries.
It can power 3 headphones at once each with their own volume controls.
It has a good many forms of inputs and outputs and even accepts XLR input.
It also runs on DC electricity. I tried it on both by the way. Batteries sounded better to me but not 100% sure there, might be placebo, not sure.
ALBEIT
Lower impedance phones like the HD 598 sound even worse compared to what I described above. And 32 ohm / IEMs will probably blow up even with the volume at the lowest setting.
It is very very loud. So loud that I would consider it a con.
I agree it has its own unique USPs that no other amp especially at this price range, has.
However, sound quality is something where it underperforms. Especially when you compare it side by side to better stuff, including the STX headphone jack that may not be a big upgrade over it but is certainly far more enjoyable.
BOTTOMLINE
I'm sending my unit back to Amazon.com. Partly because I already have 3 SS amps and one hybrid amp, and I have no intention of adding just another SS amp to my stable. Under $99, it may be very good/okay, not sure, but I don't need it right now and I don't love it enough to add it to my stable.
I'm glad I have that privilege without losing much money that I spent.
Do NOTE:
Other setups sound far closer to each other than to this one. The other setups above are not identical but given a similar volume and all that, they aren't night and day from each other.
This unit is a significant step lower than the others (maybe except the Fiio E12)
It may be able to compete under USD 100, especially for those who want to go loud with difficult to get volume out of headphones. But it surely doesn't do neither of my headphones justice.
And I'm a believer in the fact that most transparent DACs are kinda indistinguishable. Most amps are sorta close unless there is a sound signature difference or unless one is poorly designed. Cables don't make a difference.
If you want to get the most our of your headphones, a FiiO E12 isn't very good but it definitely makes the HD 650 loud enough and is far smoother. Not as clean or transparent as this, but smoother and more musical. And of course there are probably several better amps than this like O2 and many others perhaps, not heard the O2 though, so no idea whether the Superlux is better or worse.
I'd say between the Fiio E12 and Superlux, it comes down to preference. The Superlux is technically better but doesn't have Fiio's smoothness or musicality. However, when it comes to the Asus STX, it is definitely a step up from the Superlux. And when talking of Project Ember or Muses, then there isn't even a comparison.
I'd say between the Fiio E12 and Superlux, it comes down to preference. The Superlux is technically better but doesn't have Fiio's smoothness or musicality. However, when it comes to the Asus STX, it is definitely a step up from the Superlux. And when talking of Project Ember or Muses, then there isn't even a comparison.
CURRENT GEAR
Home HiFiAVI ADM 9RS
DACs
Asus Essence One Muses Edition
Asus Essence STX
iDevices
Headphone Amps
Garage1217.com Project Ember Hybrid Tube Amp
Asus Essence One Muses Edition
Asus Essence STX
Fiio E12
iDevices
Headphones
HD 650
HD 598
Earphones
Philips SHE3590BK
GEAR I ONCE HAD
Home HiFi
Aktimate Mini+
Aktimate Micro
Swan H5
Swan M50 2.1
Swan M10 2.0
Audioengine A5
DACs
Asus DX
Headphone Amps
Bravo Ocean
Fiio E11
Fiio E5
Headphones
Sennheiser RS 170
Sennheiser HDR 180 with TX 170
HD 439
Pioneer SE-A 1000
Earphones
Soundmagic E80S
Monster Turbine
Soundmagic PL50
Sennheiser CX500
And many more!