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Review and Measurements of Massdrop THX AAA 789 Amp

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I'd still stick to the 789, used it can be had pretty decently priced. If you want shoot me a PM I've got a great condition one and an SU-8 I could part with.
Thanks. I am purchasing new due to return policies.

I just realized the dx3 pro I have is 10 ohm output resistance. Not the measured 1 ohm from v1. So it is going back since I primarily drive low ohm headphones so far.

I actually might keep it as the DAC. Depending on what replaces it for amp.
 

Svperstar

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Given that the dac tool seems to be down, is there any other amp with more power and better ratings than this one anywhere near this price?

This looks like it can drive anything from low ohm headphones to high ohm, whatever. (My dx3 pro is already proving under powered, and I need to fix that)
SMSL SP200 is also THX and only measures slightly worse then the 789 and I believe it has slightly more power; its also cheaper.

Subjective reviews say the 789 "sounds better" then the SP200. I can't verify that either way.
 
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SMSL SP200 is also THX and only measures slightly worse then the 789 and I believe it has slightly more power; its also cheaper.

Subjective reviews say the 789 "sounds better" then the SP200. I can't verify that either way.
Yep. The price difference isn't enough to matter to me (at least not at amazon prices currently). But, if all I am going to end up doing in a month is buying an a90 because headphone y needs it, I'd rather just do that now. Even if it means keeping the dx3 pro as dac.

Just trying to make sure there are no headphones that the 789 can't drive well on my radar.
 

dreadknot

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Given that the dac tool seems to be down, is there any other amp with more power and better ratings than this one anywhere near this price?

This looks like it can drive anything from low ohm headphones to high ohm, whatever. (My dx3 pro is already proving under powered, and I need to fix that)
id go with the schiit magnius

id its great near same power at each ohm plus some more ohm options


https://www.audiosciencereview.com/...he-schiit-magnius-sub-500-balanced-amp.15778/
 

gvl

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JDS Labs ATOM is a good interim solution as others suggested and inexpensive, especially when bought used.
 

phoenixdogfan

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For me the 789 is a sunk cost. I need pay nothing from here to enjoy completely transparent headphone amplification. Makes no difference if something comes along with slightly better inaudible distortion numbers or lower cost. My headphone amplification needs are taken care of for life as far as I am concerned.
 
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For me the 789 is a sunk cost. I need pay nothing from here to enjoy completely transparent headphone amplification. Makes no difference if something comes along with slightly better inaudible distortion numbers or lower cost. My headphone amplification needs are taken care of for life as far as I am concerned.
In which case, I am fine with it. But, are we sure it can drive any headphone on the market? I mean, I picked the dx3 pro because it would drive anything I am "likely" to have and it's already in question now that I plugged sundara's into it.

(Side note, I actually don't think the amp upgrade will make much of a difference with sundara, but it could with other headphones I am considering)
 

Jimbob54

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In which case, I am fine with it. But, are we sure it can drive any headphone on the market? I mean, I picked the dx3 pro because it would drive anything I am "likely" to have and it's already in question now that I plugged sundara's into it.

(Side note, I actually don't think the amp upgrade will make much of a difference with sundara, but it could with other headphones I am considering)
What else are you considering? Do you listen loud? I wouldn't have thought the Sundara should be a challenge for the dx3
 
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What else are you considering? Do you listen loud? I wouldn't have thought the Sundara should be a challenge for the dx3
ath-r70x, quad era-1 (which reviewers have stated "good" amp, but it's not clear dx3 pro doesn't qualify)

Both of those arrive this week. But other hard to drive planars are on the "might go here next" list.

One problem, is this version of dx3 pro has the 10 ohm output impedance. which could be a problem for sundara (I do hear hiss when in high gain sometimes, since dx3 is noisless, I imagine this has to be gain/source issue?) as well as the quad.

I have no issue with volume on sundara in high gain mode. And, honestly, listening loud definitely makes it better as well. But I don't want to listen that loud all the time.
 

Jimbob54

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ath-r70x, quad era-1 (which reviewers have stated "good" amp, but it's not clear dx3 pro doesn't qualify)

Both of those arrive this week. But other hard to drive planars are on the "might go here next" list.

One problem, is this version of dx3 pro has the 10 ohm output impedance. which could be a problem for sundara (I do hear hiss when in high gain sometimes, since dx3 is noisless, I imagine this has to be gain/source issue?) as well as the quad.

I have no issue with volume on sundara in high gain mode. And, honestly, listening loud definitely makes it better as well. But I don't want to listen that loud all the time.
I'd get the 789. But be prepared to go balanced, don't buy it for single ended only. Get the L30 or similar for that.
 
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I'd get the 789. But be prepared to go balanced, don't buy it for single ended only. Get the L30 or similar for that.
No balanced for now. Not sure that's an issue on the drop version though. the other one doesn't do well for single ended.

L30 is a good short term solution with the dx3 pro.
 

Jimbob54

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No balanced for now. Not sure that's an issue on the drop version though. the other one doesn't do well for single ended.

L30 is a good short term solution with the dx3 pro.
I was thinking balanced so you know you have that much more power on tap if that's what will make you comfortable. But then you'd really want a balanced dac too so up goes the cost.
 
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I was thinking balanced so you know you have that much more power on tap if that's what will make you comfortable. But then you'd really want a balanced dac too so up goes the cost.
Right, exactly. If I am ready to say "screw cost", I'd just buy the d90/a90 stack and call it a day. As of now, I have zero interest in balanced if I don't need it for power. (If I do, then it's a whole different game)

Either way I will return the dx3 pro most likely because of the output impedance and pick something else. Just haven't picked *what* yet. I am limited to things that I can get here quickly though.
 

Dana reed

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Right, exactly. If I am ready to say "screw cost", I'd just buy the d90/a90 stack and call it a day. As of now, I have zero interest in balanced if I don't need it for power. (If I do, then it's a whole different game)

Either way I will return the dx3 pro most likely because of the output impedance and pick something else. Just haven't picked *what* yet. I am limited to things that I can get here quickly though.
If you have zero interest in balanced, then either the atom or heresy is the way to go. Either one is $99 and will drive most anything. The heresy having a little more power, with a little higher distortion, but still probably not enough difference between them to make the decision. I don't have either one, as I'm one of those cretins that chose a magni 3+, mainly because it was silver, and my other stuff is silver, and I probably wouldn't be able to tell the 3+ apart from the atom or heresy anyway.
 
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If you have zero interest in balanced, then either the atom or heresy is the way to go. Either one is $99 and will drive most anything. The heresy having a little more power, with a little higher distortion, but still probably not enough difference between them to make the decision. I don't have either one, as I'm one of those cretins that chose a magni 3+, mainly because it was silver, and my other stuff is silver, and I probably wouldn't be able to tell the 3+ apart from the atom or heresy anyway.
Yep! I am going to wait until I try the other two headphones that are coming in on my DX3 Pro. Then decide where I want to go.

Currently I am getting this feeling that people put too much emphasis on the amp. I do wish that there were better tests for the power required for a given headphone. It is currently impossible to tell from the specs alone. Example, some low ohm planars are easy to drive and some are hard? Why? I assume volts/amps. Shouldn't there be some test that lets us determine that?

Anyway, I suspect the next selection will be a stack, not a combo. All the stacks seem to have far more power than the corresponding combos. And I'd rather do that and know it's there. The 50s stack (with p50 for convenience) is looking very good to me right now. I am a bit surprised the a50s doesn't have more power though.
 

Dana reed

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Example, some low ohm planars are easy to drive and some are hard?
I mean some transducers are just more efficient than others. That's usually something listed on the specs of the headphone. Innerfidelity used to have a whole bunch of headphone measurements and one of the things they did was measure the output at both 1 mW and 1V. But that site seems to have gotten absorbed into stereophile and I can't find those measurements any more.
This site now has a bunch of them:
https://diyaudioheaven.wordpress.com/headphones/measurements/

For instance you can see a really hard to drive planar (74 dB/mW 86 dB/V)
https://diyaudioheaven.wordpress.com/headphones/measurements/hifiman/susvara/
And a really easy to drive planar (103 dB/mW 120 dB/V)
https://diyaudioheaven.wordpress.com/headphones/measurements/audeze/lcd-x-fazor/

You can use those numbers and then add 3 dB for each doubling of power from that 1 mW reference. So to get the Susvara to the same output as the LCDX, you have to get 29 more dB. If we round that up to 30, you've got to double the power 10 times. So you need ~1 watt at the impedance of the susvara, which is 60 Ohm. The Heresy specs at 1.6 W at 50 Ohm, so you're probably there, to get 103dB output. Considering they spec 2.4 W into 32 Ohm, and Amir's measurements bear out that you can get that before clipping, the 1.6 into 50 Ohm is a good bet.
The Atom specs 1 W into 32 Ohm, so you won't be able to get as loud into the Susvara before clipping.

All this said, if you're buying something as crazy as the Susvara, you can probably swing a bigger amp than these $99 guys.
If you're running the HE560, or LCD2, or LCDX, either of these amps will melt your ears.
 
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I mean some transducers are just more efficient than others. That's usually something listed on the specs of the headphone. Innerfidelity used to have a whole bunch of headphone measurements and one of the things they did was measure the output at both 1 mW and 1V. But that site seems to have gotten absorbed into stereophile and I can't find those measurements any more.
This site now has a bunch of them:
https://diyaudioheaven.wordpress.com/headphones/measurements/

For instance you can see a really hard to drive planar (74 dB/mW 86 dB/V)
https://diyaudioheaven.wordpress.com/headphones/measurements/hifiman/susvara/
And a really easy to drive planar (103 dB/mW 120 dB/V)
https://diyaudioheaven.wordpress.com/headphones/measurements/audeze/lcd-x-fazor/

You can use those numbers and then add 3 dB for each doubling of power from that 1 mW reference. So to get the Susvara to the same output as the LCDX, you have to get 29 more dB. If we round that up to 30, you've got to double the power 10 times. So you need ~1 watt at the impedance of the susvara, which is 60 Ohm. The Heresy specs at 1.6 W at 50 Ohm, so you're probably there, to get 103dB output. Considering they spec 2.4 W into 32 Ohm, and Amir's measurements bear out that you can get that before clipping, the 1.6 into 50 Ohm is a good bet.
The Atom specs 1 W into 32 Ohm, so you won't be able to get as loud into the Susvara before clipping.

All this said, if you're buying something as crazy as the Susvara, you can probably swing a bigger amp than these $99 guys.
If you're running the HE560, or LCD2, or LCDX, either of these amps will melt your ears.
Yeah, it's the combination of db/mW and dB/V that really makes it make more sense. I assume the ones that have low ohm and reasonable sensitivity (like 95dB) but are still hard to drive probably have a low dB/V ratio. Does having both of these inform on the amp requirements?

That said, the dx3 should melt my ears on the lcd-x-fazor by these numbers. The lcd-x is pretty high on my list of headphones to audition (and rising).

While there is a money limit, for me, it's definitely more about finding the *right* setup. If what I determine is "right" is also outside of my current ability to purchase, I'll figure out a path to get there. For example, an e30/l30 stack is a phenomenal option when I know it's a placeholder until I justify an a90/d90 stack. But some of these other options get way to close to an a90 + e30 which seems like a phenomenal pairing and is half of the full goal. That's just an example.

Right now I don't know what the goal is. I just know the dx3 pro likely isn't part of it (except maybe as a DAC).
 
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20201114_091526.jpg



@amirm, in your "Headphone Amplifier Signal to Noise Ratio at 50 mV" graph, you had shown:

"MassDrop THX AAA 789" achieving 90

and also

"Drop THX AAA 789 Bal" achieving 84

Is the SNR of 90 achieved with single-ended headphone output? If that is the case, does it mean that single-ended headphone output has better performance than balanced headphone output?
 
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