• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of Massdrop THX AAA 789 Amp

Joined
Aug 6, 2018
Messages
26
Likes
14
Location
Sweden
Sure. Thanks for the idea. :)

Here it is the link: https://www.massdrop.com/?referer=DA3TGL

Anyone who uses it gets $10 discount if they are not a member already.

FYI I just bought THX unit. :)
Just ordered it using your link, thanks for saving me $10 :) But do you know why your measurement of SNR differs by 13 dB compared to the stated specs? Did they just overstate the specs or did you measure it in a different way compared to them? I see that they stated that it was done at 300 ohms, <1% THD, is that the same way you measured it? Not that I think it makes any audible difference, just curious :)
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,793
Likes
18,530
Location
Seattle Area
But do you know why your measurement of SNR differs by 13 dB compared to the stated specs?
SNR measurements can be highly variable depending on how they are performed. I routinely get different measurements than what is stated. SO I would not at all worry about that.
 

Roen

Addicted to Fun and Learning
Joined
Oct 14, 2018
Messages
542
Likes
169
Would the THD+N and SINAD numbers be better if the gain is turned down to 2 or 1?
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
18,793
Likes
18,530
Location
Seattle Area
Would the THD+N and SINAD numbers be better if the gain is turned down to 2 or 1?
All amps are quieter if you reduce the gain. As long as you don't need the extra power, it is best to run in the lowest gain possible.

That said, looks like I did not measure that difference. I will do so when I get a chance.
 

gvl

Major Contributor
Joined
Mar 16, 2018
Messages
1,034
Likes
593
Location
SoCal
I pulled the trigger but having second thoughts. I have the O2. will I be "blown away" by this? Ok, maybe not blown away, but will the differences be apparent on low to medium volume levels with the HD 6XXs?
 

gvl

Major Contributor
Joined
Mar 16, 2018
Messages
1,034
Likes
593
Location
SoCal
Or don't need the balanced input for some reason.
I could find use for it, but no, I don't really need it. Too bad it doesn't have variable outputs, it would work nicely for my needs and would be another reason to get it. Also it needs one extra 1 inch across that I don't have on my desk. Oh well, sounds like this was not meant to be, I know I will regret it later.
 
Last edited:

helloworld

Active Member
Patreon Donor
Joined
Jul 10, 2018
Messages
199
Likes
131
unfortunately this amp does not have the 3pin xlr out. What’s the difference between using a 4 pin xlr to 2x3 pin xlr connector vs real 3pin xlr balance output?
 

helloworld

Active Member
Patreon Donor
Joined
Jul 10, 2018
Messages
199
Likes
131
These 4-pin XLRs are for headphones only. They have nothing to do with balanced interconnects with 3 pins.
In monorpice thx DAC Q&A section, Andrew M said we can wired the XLR-4 headphone out pins to the two XLR-3 balanced in to make them XLR-3 balanced out. So it looks like to me the XLR-4= 2*XLR-3 but with worse grouding, am I right? If so I could buy a XLR-4 to 2xXLR-3 cables and use this amp as a preamp.
Thanks
1542156552762.png
 

maverickronin

Senior Member
Joined
Jul 19, 2018
Messages
461
Likes
333
Location
Midwest, USA
If so I could buy a XLR-4 to 2xXLR-3 cables and use this amp as a preamp.
You wanted to use an external adapter on the main headphone out? That would be awkward, but it would work.

Do you guys think this amp has enough power for the Susvara or HE-6?
I'm not sure if anyone has any real efficiency measurements on the Susvara (HiFiMan is always overly optimistic...) but the pair of HE-6's measured on Innerfidelity was around 77dB/mW. This amp is amazingly clean to 3.5W into 50 ohms from the 4 pin XLR which should be good for ~112dB SPL on the HE-6.
 

Headphonaholic

Active Member
Patreon Donor
Joined
Apr 8, 2018
Messages
222
Likes
259
I got an email that the massdrop thx amp is in stock at the moment! I immediately jumped on it. I honestly didn't expect it to come back around so soon... guess I'll be passing on the monoprice one!
 
Joined
Oct 31, 2018
Messages
13
Likes
15
Coming from a Schiit Ragnarok, with HD 800 as my main headphones, what should I expect from this amplifier? My first guess would be that the channel balance on the Ragnarok should be slightly better as it is discretely controlled via relays.

I understand that measurements aren't directly transferable between different websites, so even having read Stereophile's measurements I don't really know what to make of the differences; I really hope someone with more experience might be able to shed some light on this comparison. Thank you very much!
 
Top Bottom