Massdrop x THX AAA 789

I'm seriously tempted by this amp, but of all things, the integrated PSU bothers me a great deal. For whatever reason, these types of power supplies fail (I imagine cost of manufacturing) and I don't want to have to attempt some difficult repair instead of just finding another suitable one online.

I'm also curious if the Jot will see another upgrade in the not-too-distant future given the improvements found in Lyr 3 and popularity of the model.

Is the Lyr 3 a clear upgrade over this THX model for those who don't want balanced?

 

Just want to put this on record (ok to call me pussy): I'm canceling my order on the unit. The sound I bet will be good but I honestly don't think I can wait until Feb to get my unit. Oh well, patience is a virtue.

 

Will probably put mine up for sale. Got impatient and picked up the Benchmark HPA4 which is the flagship for the thx amps. If this amp is 90% of the HPA4.. it's a killer deal.

 

For the price and with marvs kind words.. I'm in! Though I hate switchers.. I've heard that PSUs play a huge influence on SQ so switching to linear on this may have (or may not, due to the THX technology?) benefits. Regardless, I'm down for the wait.

 

Phew... Sorry for the late report. I got sidetracked while in Vietnam (and I'm still a bit preoccupied now), but... long story short: I heard this amp a bit ago at Massdrop HQ and wrote down some notes on it. I liked it so much that I asked @CEE TEE if I could borrow a unit while I'm in Nam. So disclaimer: I wasn't asked to write these words.

So 2 months later, I finally have some time to check the amp out, and just as last time, it blows me away.

Some may think this is a super O2, but done in a very nice way. I would have to... somewhat disagree. I brought along an MCTH for some tubey goodness. This is the perfect amp to compliment the MCTH, and I think it sounds more like how Cavalli would do an O2 type amp.

I haven't gotten the chance to compare the THX against an O2, but I'd bet the only thing it has in common with O2 is the cleanliness. Everything else sounds... very different with this amp. Will try to find O2 to compare against soon.

I would describe this amp as being highly transparent, almost see-through, but with good solidity + fluidity and just about enough impact and weight. Jotunheim sounds more weighty and impactful from memory (using my custom modded HD800 and HE-4XX) but I think the THX does soundstage better. It actually sounds like it has depth with HD800, unlike Jotunheim which can sound a bit flat. I think Jotunheim can sound a bit fuller/warmer and more forward compared to this amp.

That's not to say the THX sounds laid back. It's kinda aggressive, actually, but it's a calm aggressiveness, if that makes sense.

Even with HD800, the THX barely sounds sharp, and instead, it just sounds... fast. A friend of mine who I invited to check the amp out said that the HD800 + THX combo sounds almost like an e-stat, and I'd agree. There's something ethereal about the way the THX controls the HD800's drivers.

So now I'm sold. Even if I have to wait until next year, Feb or whichever, I'll definitely join the next drop. This is basically how I wanted Jotunheim to sound like. The THX is my next favorite solid-state amplifier.

Will try to plug Andromeda and other such IEMs into it soon. But so far, even with shitty no-ground Vietnam electrical system, the amp sounds very impressive.

Brief comparison against MCTH: basically a lot more airy and a lot faster sounding, although at the risk of maybe making HD800 a bit too ethereal for certain genres of music. I'd say MCTH might be better for when I want to "slow it down", but THX is the overall more technical and better performer to my ears.

Hey, @CEE TEE, congratulations, man!! I'm really loving what you're doing!

 

I had expected some reviews on here by now hope some knowledgeable people chime in about its sound.

So far I read some short "very pleased" comments with people starting to receive theirs. But also more than one person that had humming/grounding issues connecting balanced xlr inputs to the THX AAA. Hope that is an interconnect/source issue rather than a big problem with the amp itself.

 

Just got my sample in this morning. Listening and will compare later with the AHB2s.

 

First impressions:
Manual says it doesn't need any burn-in, so after getting it to room temperature here we go. Live stream of impressions - I reserve the right to reconsider and change my mind on any of these points.

Summary:
Pretty great (delete) amazing sounding little amp and what a headamp should be. Affordable, cheerful, has all the connectivity you need. It has similar traits to the Benchmark AHB2s, and comes within sight, but does not meet the overall performance of the AHB2s in technicalities. That however does not detract from the overall attractiveness of the 789 amp. It is a really great amp in its own right, with impressive clarity, dead quiet, a 3d stage that many other solid states wish they could have and my first thoughts are the performance more than exceeds its pricing.

Headphones: Modded unicorn (4 screw) HE-6s, why bother testing proper amplifiers with lesser easy to drive headphones.

Massdrop THXAAA 789: balanced output, balanced input from my MSB DAC V, MSB preamp off, so using the 789 volume control
2x Benchmark AHB2 bridged monos: balanced output (adapter made out of same cable I use for HPs) balanced inputs from MSB DAC, MSB Diamond preamp

First question: Can the little amp drive the HE-6s? It's pretty good actually. No crushed stage (check), No thin bass (check), No tizzy hysteric treble (check). The HE-6s on the 789 sound a hint warmer from my idea of neutral and smoother/a bit more liquid than what I am used to.

Tonality: close, relatively neutral on both and mostly sounds like whatever your source sounds like. I note a difference in the bass, the 789 has slightly more bass quantity/oomph, but the AHB2s have better bass resolution/speed/dynamics. The treble is similarly clean of artifacts/grain/harshness/bullshit associated to many a solid state.

Soundstage: 789 has really nice 3D front to back layering (reminds me of the 2A3 EC amp I had), but the stage is smaller left to right, and not as open and airy sounding as the AHB2s.

Clarity/Transparency: Like its bigger brothers the 789 sounds impressively clean/clear/quiet, but there is a slight softness/smoothness compared to the AHB2. This could be the budget pot. Both amplifiers also have this chameleon like character based on recording material that I really love: on calm music/passages they sound nice and relaxed, but when the content changes and out of seemingly nowhere they are hard hitting and very impactful. Between these two the 789 has the overall more relaxed/liquid character. While the 789 has an amazing A+ level of see through, the AHB2s are A+++.

Imaging: The 2xAHB2 image like GODS. I use them mainly with speakers, but that's the case with headphones too. The 789 is at about 80% of the AHB2s in terms of imaging precision.

Transient response: Both these amps can hit hard when asked. But the 789 sounds a bit slower, softer and more liquid than the AHB2s and does not match the latter's transient impact/hit. It's probably still more precise and impactful than a lot of solid states out there, but for me being a HE-6 listener, I prefer the AHB2s on this point. On that train of thoughts, I can see this amp working better with HD800s than the AHB2 does. The reverse would be true with Audeze and HD650 for example.

Resolution/plankton: The AHB2s are more transparent, clearer, cleaner and resolve finer details better.

Keep in mind a couple of things here:
- The 789 is only a few hours out of the box. I know they say burn-in voodoo doesn't exist, but I will revisit this comparison after a few days.
- The preamplification is a not a fair contest. 789 budget pot vs MSB Diamond preamp option. A more fair contest would be bypassing the 789 volume control completely, but I imagine the vast majority of folks will use the 789 as is. I might have slightly different plans with this amp in the future, but that's a different conversation for another time.

When I get time I will compare the HD650M, but right now I don't want to, because this is thoroughly enjoyable with the HE-6s, and the extra murk of HD650 doesn't do these amps justice.

 

It's also dead quiet with both my Prophile 8 and Layla IEMs. Both of them scale really well with this amplifier, but I was impressed in particular how much the Prophile 8 scaled with the 789 over the Leckerton, with whatever opamps @frenchbat has in this: tighter/more precise imaging, improved scale and layering, better dynamics, clean background highlighting contrasts, detail levels, no opamp fog etc

Both these IEMS have frankly amazing staging and imaging capabilities with the 789 amp. The PP8 image is seriously expansive and precise, so much that it shames some full size HPs on lesser amps. I didn't think PP8 would scale much over my DX200 and/or Leckerton, but learnt something new today.

 

ADA4627-1A Opamps. I heard from my associates that there's better out there now, but I don't really have much interest anymore.

 

Day two, sounds exactly the same.

With the HD650 (kiss/coin mod, silver wires) I am missing the AHB2's superior transient attack/hit, detail levels, imaging focus and stage openness. These things bridge the HD650s into higher-fi. To be fair the 789 does give some good hints of what is possible, but it's slightly relaxed/softer nature is less than ideal with HD650. By my personal biases the 789 is more suited to more assertive sounding headphones, and I would not be looking at matching HEK, HEX and that kind of things with this. But keep in mind it is quite neutral sounding with just a bit of bass coloration.

Still there are many great aspects about the 789 pairing with HD650: amp's background darkness, clarity, 3D, clean smooth treble, neutral tonality, but never sterile sounding. These are all areas where the headamp's peformance is into higher-fi territory and once we are reminded the level the amp is priced at, I don't think there's much to complain about from a sound quality point of view.

But also based on what I've heard so far, I am thinking there is room performance wise for a Massdrop headamp offering based on THX888 modules with an improved volume control solution.

 

This could explain with some of the differences I am hearing vs AHB2. And it may be a good thing, or not, depending on context and preferences.

https://www.audiosciencereview.com/...easurements-of-massdrop-thx-aaa-789-amp.5001/
"Output impedance is 1.0 ohm which I would normally say is very good but given the above performance, I wish it was half an ohm lower"

https://www.stereophile.com/content/benchmark-media-systems-ahb2-power-amplifier-measurements
"The output impedance, including a 6' speaker cable, was a low 0.09 ohm at 20Hz and 1kHz, rising slightly to 0.22 ohm at 20kHz."

 

Note* that "Amir" has an inflated measured output impedance, since it travels through many cables before he ever gets his result. What he gets is generally 2-3x the "normal" value, should be taken with a grain of salt..

Still, it could be a reason yes.

 

What's the Jotunheim or Fulla output impedance measured by others, for example?

The DAC3 HGC measured by Stereophile has <0.5 across FR (wtvr that actually is) and on this other site 0.7. But yes good point and reminder measurements from different sources can be rarely directly compared.

Until we get more input, I'd look at it for now as an indication the 789 may have higher output impedance than AHB2.

Back to 789 impressions, the combination I keep going back to is Prophile 8 with this amp (not brave nor crazy enough to put IEMs on 2xAHB2). Sounds just so clear, clean, and well balanced/coherent tonally and the head (delete), IEM stage is surprisingly big and well layered. Well articulated, but subtle enough to not be drawing un-needed attention to note impact. Midrange is subtly velvety smooth, and on good quality recordings, sounds emerge from the darkest background. Absence of distortion is a wonderful thing I guess. The bass is seriously impressive in punch and weight, and I am not even using the boost switch.

The worst match is the K872 so far. It does nothing for me after listening to any of the other headphones I mentioned. Muffled, closed in and lack presence.

 

http://www.freepatentsonline.com/9071201.html
I think I have found the thx patent for anyone who has the capability to find out something about the topology

 

Or that resistor is part of the crazy DC servo Alex uses for input and output. Like it monitors the voltage or offset across that 1 ohm resistor. Just trying to think out loud. IDK

 

Heads up to anyone ordering from Europe, massdrop classify these as something other than electrical amplifiers so it falls under the trade war tariffs, either try to get them to classify it right straight away or make sure to claim back customs duty if you have to pay to receive it and then claim back.

It should be 1.1% here and they gave me about 12.5%

 

That is what I paid and raised a claim, but I haven't heard back on it yet.

 

Drop is up again same day shipping. The time is meow.