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Review and Measurements of Massdrop THX AAA 789 Amp

Schackmannen

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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 :)
 
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amirm

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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

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Would the THD+N and SINAD numbers be better if the gain is turned down to 2 or 1?
 
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amirm

amirm

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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

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OMG, it is dropping now ready to ship in 1 day! Suspiciously good timing ;)
 

gvl

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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?
 

maverickronin

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Or don't need the balanced input for some reason.
 

gvl

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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.
 
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helloworld

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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

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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
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maverickronin

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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

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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!
 
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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!
 

Ariamella

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Anyone know how this compares to the Project Ember II? Thinking of getting this as a replacement for that.
 
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