Review and Measurements of Massdrop THX AAA 789 Amp

[bequietjk]

My bad i didnt consider the performance of my dacs outputs.

What i want to clarify is that i find a difference in sound when using the balanced input vs the unbalanced on the 789, but what must also be considered is the performance of the dac being used as time and time again, not all dacs balanced + unbalanced outputs are created equal.

 

[zepplock]

My bad i didnt consider the performance of my dacs outputs.

What i want to clarify is that i find a difference in sound when using the balanced input vs the unbalanced on the 789, but what must also be considered is the performance of the dac being used as time and time again, not all dacs balanced + unbalanced outputs are created equal.

Performance is (in 99% cases) FR, power/clipping/loudness, channel imbalance/crosstalk. You have to consider which one changes when you compare A to B. If for any reason you end up with just "listening" you have to make sure your loudness is normalized. Otherwise it's impossible to compare anything just by listening.

edit: lol lowndness

 

[Rottmannash]

My chain is PC via Audirvana > D70 > balanced to THX 789. Typically listen balanced to HP's and the power on gain 1 and gain 2 is very impressive, even with power hungry cans. Have never used gain 3. Have never sent the signal from the DAC to the amp unbalanced so can't speak to that.

 

[Azeendeen]

Hey guys, after I turn on my 789 amp, is it normal to hear one click sound followed by the led signal turning on? ONLY 1 click sound. I thought the click was to show it had turned on right. I have been using it fine since early 2019

Because I was on another thread for another amp, the L30. I said both the L30 and THX 789 made one click noise after turning on. I was told clicking noise in amps are bad and could mean they're broken and could lead to headphone damages

 

[Rottmannash]

The click is a relay- normal as far as I know. Why would you think everyone's amp is broken because they click?

 

[Azeendeen]

The click is a relay- normal as far as I know. Why would you think everyone's amp is broken because they click?

Yeh it was a misunderstanding in the other thread. Later they clarified that they meant the click noise is normal as a relay.
My bad

 

[Rottmannash]

Ah. Good.

 

[raistlin65]

I'm quite enjoying my 789. It addresses the main reason I decided to upgrade over my Atom amp: the THX 789 does not want to fishtail all over the place when plugging and unplugging headphones. I also like the volume knob better because it's longer (I have big fingers). And I'm enjoying not having to unplug my headphones to listen to my speakers or even having to turn the 789 on. The passthrough is a plus given I didn't need preamp capability.

Sonically, for $100, the Atom is the better choice since there is no audible difference. But I am happy with spending the extra money for the THX 789 from a user-friendliness perspective.

BTW: Using the Tempotec Sonata HD Pro as my DAC. Works great with the THX 789.

 

[Veri]

The only things I disliked about the knob is the low weight, and eventual scratchiness at initial turn. Otherwise it's a fine amp indeed.

 

[zepplock]

The only things I disliked about the knob is the low weight, and eventual scratchiness at initial turn. Otherwise it's a fine amp indeed.

Mine is pretty light but not to the point of where I dislike it. I wish it was ~20% stiffer.
No scratchiness for me. Maybe yours need some deoxit.

 

[Veri]

No scratchiness for me. Maybe yours need some deoxit.

Oh yeah good to bring that up, that fixes the issue right away, indeed My past amps did not develop this issue though. Maybe dust collects somewhere, I'm not sure of the cause.

 

[zepplock]

Oh yeah good to bring that up, that fixes the issue right away, indeed My past amps did not develop this issue though. Maybe dust collects somewhere, I'm not sure of the cause.

I spray deoxit everywhere, works on mechanical keyboards really well too!

 

[Rottmannash]

I spray deoxit everywhere, works on mechanical keyboards really well too!

Dumb question- is deoxit the same as contact cleaner?

 

[zepplock]

Dumb question- is deoxit the same as contact cleaner?

yes

 

[Damian]

I couldn't find the answer googling, but is there any sound quality difference between the gain I, II and III provided the volume output is normalized?

 

[Rottmannash]

I couldn't find the answer googling, but is there any sound quality difference between the gain I, II and III provided the volume output is normalized?

I haven't noticed-just more and more power as one switches from 1 to 2 then 3. I know when using equalization and watching streaming videos I need to go to gain 3 due to the equalization applied and the apparent lower volume coming from various sites while streaming concerts. I can't discern a difference between any of the gains - that's the short answer. One gain 3 with normal level input one simply can't turn it up high enough to hear distortion-it would be torture.

 

[Jimster480]

I couldn't find the answer googling, but is there any sound quality difference between the gain I, II and III provided the volume output is normalized?

I've tested and not been able to discern a difference.

 

[Cosmic Heretic]

I'm quite enjoying my 789. It addresses the main reason I decided to upgrade over my Atom amp: the THX 789 does not want to fishtail all over the place when plugging and unplugging headphones. I also like the volume knob better because it's longer (I have big fingers). And I'm enjoying not having to unplug my headphones to listen to my speakers or even having to turn the 789 on. The passthrough is a plus given I didn't need preamp capability.

Sonically, for $100, the Atom is the better choice since there is no audible difference. But I am happy with spending the extra money for the THX 789 from a user-friendliness perspective.

BTW: Using the Tempotec Sonata HD Pro as my DAC. Works great with the THX 789.

The passthrough, gain switch and volume knob are big reasons I just ordered the 789 over the SP200. It's probably my end game amp.

 

[raistlin65]

The passthrough, gain switch and volume knob are big reasons I just ordered the 789 over the SP200. It's probably my end game amp.

Yep. My first piece of audiophile electronics was an NAD 3130 Integrated Amplifier when it wasn't a vintage amp. lol

So while I can appreciate how well my Atom amp performs, I do like a little more solid piece of equipment if it's something I use a lot, with the exact features I want.

For a first amp, I think the Atom is a fabulous choice. How do people really know what they want in headphone electronics when you are first starting out?

But for someone for whom the price difference between the Atom and the THX 789 is not important to their disposable income? If they don't need a preamp out, the THX 789 is a great choice.

 

[Cosmic Heretic]

Yep. My first piece of audiophile electronics was an NAD 3130 Integrated Amplifier when it wasn't a vintage amp. lol

So while I can appreciate how well my Atom amp performs, I do like a little more solid piece of equipment if it's something I use a lot, with the exact features I want.

For a first amp, I think the Atom is a fabulous choice. How do people really know what they want in headphone electronics when you are first starting out?

But for someone for whom the price difference between the Atom and the THX 789 is not important to their disposable income? If they don't need a preamp out, the THX 789 is a great choice.

I find it hard to let go of a really good amp as it is always possible to fit them in with new gear. I still have my vintage NAD 7125 also. I love the rear mounted heat sink and small form factor still. Also I love my 11 year old THX Select 2 Onkyo 608 receiver that runs cooler than my Denon x3700 that I am pre-outing to it from. My E30 dac can act as a preamp with remote volume also for more flexibility. $300 for an amp as good as the 789 is a worthy investment IMO.