Review and Measurements of Massdrop THX AAA 789 Amp

[Veri]

@amirm I looked through the thread and couldn't find the comparison of gain modes (except for crosstalk), could you kindly show us how different gain modes fare in THX? I've read your article that generally advises using the lowest gain possible, yet it says that it depends on a particular amp. Crosstalk chart demonstrates that THX's Gain 3 is better, is it for the rest of the specs or just in crosstalk that Gain 3 is better?

Gain 1 maxed out should still have no audible crosstalk though according to @AndrewMason comment on massdrop.

 

[Sylafari]

If I have a RME ADI-2 DAC, is it ok to set the volume to max on the THX amplifier and use the digital volume control on the RME ADI-2 DAC? Or do I have the RME ADI-2 DAC at 0 dB and use the volume pot on the THX? Does it even matter?

 

[maverickronin]

If I have a RME ADI-2 DAC, is it ok to set the volume to max on the THX amplifier and use the digital volume control on the RME ADI-2 DAC? Or do I have the RME ADI-2 DAC at 0 dB and use the volume pot on the THX? Does it even matter?

I'd max the volume on the THX and control the volume on the RME. You'll get better tracking that way.

 

[Azeendeen]

wow, new drop sold out fast!

Yes bro . Luckily I joined right before it ended .

 

[Roen]

Getting a DX3 Pro for now and going to see if it runs the 6XX properly enough, if it doesn't the DX3 will serve as my DAC and I'll get the THX next time it drops

Can’t see why it wouldn’t.

 

[Baljortar]

Just got mine after a patient waiting of 7 months. Have used it with my Topping D50 and I am pretty impressed with its out of the box performance. I have the DIY Cavalli audio EHHA 1 tube hybrid, Beta 22, O2 as well as teac AI 101DA to compare it to. Among DACs I have an ODAC and SMSL M8 which I use for my speaker rig (nelsonpass B1 pre, emotiva BassX300 to ELAC UNiFi UB5). Planning to do a mix and match session by the weekend.

How can you compare it with the beta 22? I've heard that this amp is a gigant killer, and the beta 22 is well known being the king of all solid state amplifiers, because of its floating cascode class A topology.
It would be fantastic if you can give us your impressions.

 

[ReAlien]

@Audiodoc, I subscribe to the abovementioned request.)

 

[metal571]

Finally got mine set up last night. I'm not one to subjectively notice most of the objective measurements taken on this forum, but as a reviewer I wanted something with tons of power, balanced output support, and ultra clean objective measurements to upgrade to from the Magni 3. Should have pulled the trigger on this thing a lot earlier - one hell of an amp. Would be nice if it had auto-on and not just auto-off so that both my D50 and it could be automatically turning on and off when starting up/shutting down my desktop. Thanks again for all your work amir.

 

[sbsj]

This will be my next amp when it drops again. Hopefully they fix the minor hardware issues.

 

[Veri]

This will be my next amp when it drops again. Hopefully they fix the minor hardware issues.

I've zero actual hardware issues with mine, honestly. Works perfectly so far.

 

[Roen]

+1

Nice clean sound. Then again, most of my amps are clean, so I wouldn't know where to begin on non-clean sound.

 

[gtb75]

I got my 789 last Friday. No "minor hardware issues" that I have observed so far.

Initial subjective impressions are positive. Most of the listening I've done so far has been with my 6XX using balanced cables fed with a SU-8 v2 also running balanced. Heck of a amp for the price and I love the convenience of 3 gain settings and 3 headphone connector types built right in, plus it runs cool. To my ears it is more neutral and presents a wider sound stage than the Liquid Carbon, but doesn't quite match the sound stage width or separation of the Liquid Platinum. I will say that switching from gain position II to position III definitely opened up the sound stage of the 6XX on the 789. I just slightly reduced the output level on the SU-8 - which I have to do anyway with the Liquid Platinum since it doesn't have a gain switch.

I don't have a way to perform measurements, so subjective feedback is all I can offer. Again, really nice amp for $350!

 

[Memoryerror]

I felt like using earbuds as I have a pimple that my overear headphones are annoying. And I noticed a slight repeated popping sound. I have my 789 hooked up to my DX7s with xlr cables and I was on the lowest gain signal. Any idea what to try to stop it?

 

[GoMrPickles]

Hi all, first post. I bought the THX AAA 789 on the basis of Amir's measurements. It's being fed off of the RCA outputs of an O2/ODAC (Massdrop version, purchased for $155 off of Craigslist, also on the basis of Amir's measurements). Sounds great so far, and it can drive multiple headphones at once - very interesting when comparing The Sennheiser 6XX and Hifiman 4XX.

(Subjectively, ) I've preferred the 6XX, but when being driven by the THX, the Hifiman 4XX sounded much better than it did via the O2/ODAC. If anything, I feel like I'm up against the limits of recorded music (and my ears), rather than some specific weak link on my desk. I would say the THX has greater bass extension than the O2/ODAC. I don't drive them anywhere close to their limits: about 12 o'clock on the lowest gain setting for either amp.

@Memoryerror , I _may_ have heard something similar to what you're describing, but I think it also could have been my imagination. When listening to streaming media over Spotify/Tidal/Roon/etc., it's also really hard to blame the headphone amp rather than the software, Mp3/Ogg compression, DAC, or anything else in the line.

As an aside, my computer speakers are an old set of Klipsch THX 2.1 speakers. The THX 789 manuals says not to "drive loudspeakers" with it, but the Klipsch THX speakers are powered: is there any issue with using the SE out from the THX 789 to the audio in on the Klipschs? "Theoretically," it sounds pretty nice, although it's a chain with like 4 volume controls in it.

 

[AresHarvest]

The THX 789 manuals says not to "drive loudspeakers" with it, but the Klipsch THX speakers are powered: is there any issue with using the SE out from the THX 789 to the audio in on the Klipschs? "Theoretically," it sounds pretty nice, although it's a chain with like 4 volume controls in it.

The idea is to not drive passive loudspeakers with the headphone outputs of the amp. You can surely use the SE PASS outputs to feed anything that expects line-level signals, such as a set of self-powered speakers or a desktop 2.1 system. In these cases, you're feeding the built-in amplifier(s), not the speakers themselves.

 

[GoMrPickles]

The idea is to not drive passive loudspeakers with the headphone outputs of the amp. You can surely use the SE PASS outputs to feed anything that expects line-level signals, such as a set of self-powered speakers or a desktop 2.1 system. In these cases, you're feeding the built-in amplifier(s), not the speakers themselves.

Cool, that's what I figured. Thanks!

 

[Memoryerror]

@Memoryerror , I _may_ have heard something similar to what you're describing, but I think it also could have been my imagination. When listening to streaming media over Spotify/Tidal/Roon/etc., it's also really hard to blame the headphone amp rather than the software, Mp3/Ogg compression, DAC, or anything else in the line.

I had the input to my DX7S DAC paused and could hear the noise. I could also hear it while playing music.

Edit: I switched over to RCA cables (I am using the XLR for my Stax energizer now). I found that it goes away when I have the RCA passthrough disconnected (they are connected to my speaker amp). Maybe it is a ground loop with the speaker amp, it use to be connected directly to the DX7s (the speaker amp is off).

 

[GoMrPickles]

I had the input to my DX7S DAC paused and could hear the noise. I could also hear it while playing music.

Interesting. I don't hear anything like that. I don't have an XLR DAC, so I can't replicate your setup, but maybe someone else could?

 

[FunctionalDoc]

My amp just died today and I was in on the first drop received mine on October 2018 and have serial number 00440 .

Pop while listening to my ZMF Auteur's on 2nd power level as usual and got the red light display and immediately powered down and smelled something burned out. Fortunately my headphones are fine so the safety relays did their job.

Not having for a full 3 months is tarting me to wonder if the replacement will last longer. I like the amp a lot .

Will see how Massdrop handles the warranty replacement process.

Any one have else have one the original drop units and gone up in smoke?

 

[pos]

Pop while listening

ouch
Was it a loud pop?