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Review and Measurements of Massdrop THX AAA 789 Amp

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I'm looking into acquiring a 789, but I don't plan to get a DAC for now, if I connect it using 3.5mm to RCA will I get the benefits of balanced output? or balanced output requires balanced inputs?
 

raistlin65

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I'm looking into acquiring a 789, but I don't plan to get a DAC for now, if I connect it using 3.5mm to RCA will I get the benefits of balanced output? or balanced output requires balanced inputs?
What do you think the benefits are of balanced output and why do you need it?

A lot of people don't really need balanced, but seem to think that they will drive some sound quality benefit from it.

Moreover, there are single ended amps that will drive 99% of headphones and offer the same sound quality for less money.

So what is it about the 789 that you think you need?
 
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What do you think the benefits are of balanced output and why do you need it?

A lot of people don't really need balanced, but seem to think that they will drive some sound quality benefit from it.

Moreover, there are single ended amps that will drive 99% of headphones and offer the same sound quality for less money.

So what is it about the 789 that you think you need?
I understand your points, for my current needs the Atom is perfect but I have a different reasons to consider 789:
- Due to current pricing/shipping/customs what I will pay for a new Atom can get me close to a 2nd hand THX
- In my country I can't resell audio equipment, the market doesn't exist. So I'd rather get something that I would use for as long as possible, 789 with a good DAC can drive almost any headphones or speakers I might get in the future, so I don't have to buy new gear and have old gear that I won't use or sell.
 

raistlin65

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I understand your points, for my current needs the Atom is perfect but I have a different reasons to consider 789:
- Due to current pricing/shipping/customs what I will pay for a new Atom can get me close to a 2nd hand THX
- In my country I can't resell audio equipment, the market doesn't exist. So I'd rather get something that I would use for as long as possible, 789 with a good DAC can drive almost any headphones or speakers I might get in the future, so I don't have to buy new gear and have old gear that I won't use or sell.
Just to note that a headphone amp can't drive speakers. Only a speaker amp can do that.

But if you mean you want the capability to hook up active pro audio speakers, that is a good reason to go with a balanced setup. Some pro audio speakers (e.g. JBL LSR series) are prone to picking up PC noise when used with unbalanced connections. But with other speaker setups, unlikely to help.

As for the notion of being able to drive almost any headphones, the headphone community always moves to the latest, most powerful amp and hypes it that way, as well as promoting the general sentiment that balanced is the only solution for driving difficult headphones.

Single-ended amps such as the Schiit Heresy come very close in headphone amp performance to the 789. And even the Atom has sufficient power to drive 99% of headphones.

So personally, I would not focus on "balanced" since you are looking at the used market. There are many amps, some of which are not balanced, that can meet your needs for driving future headphones. I would look at everything about an amp.
 
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Just to note that a headphone amp can't drive speakers. Only a speaker amp can do that.

But if you mean you want the capability to hook up active pro audio speakers, that is a good reason to go with a balanced setup. Some pro audio speakers (e.g. JBL LSR series) are prone to picking up PC noise when used with unbalanced connections. But with other speaker setups, unlikely to help.

As for the notion of being able to drive almost any headphones, the headphone community always moves to the latest, most powerful amp and hypes it that way, as well as promoting the general sentiment that balanced is the only solution for driving difficult headphones.

Single-ended amps such as the Schiit Heresy come very close in headphone amp performance to the 789. And even the Atom has sufficient power to drive 99% of headphones.

So personally, I would not focus on "balanced" since you are looking at the used market. There are many amps, some of which are not balanced, that can meet your needs for driving future headphones. I would look at everything about an amp.
Yes, sorry I meant as preamp.

I understand "balanced" can be a marketing buzzword and many products implement it badly just to slap "balanced" on the box. I generally follow value, living in a country where minimum wage is the price of a new 789 I have some immunity against hype, even if I can afford it, it makes me feel bad :)

For the ~$100 family of amps I wouldn't get them 2nd hand, and to anyone outside the US they're bad deals because:
- Not a significant drop from MSRP, usually go for $80-90
- Currently JDS and Schiit are only shipping express which is expensive
- Require additional 220V plug because you will only find those offers for 110V, so another shipping bill unless you found a kind seller who would do you the favor of consolidating the packages

So not worth it at all 2nd hand, though $250-300 amps like SMSL SP200 and Drop 789 go for $160-220 and take 240V, that's a nice value IMO.
 

bequietjk

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Oh yeah. To my ears, soundstage width is a bit greater and the noise floor seems to be lower. The soundstage being wider could be a symptom of a lower noise floor with balanced input. The best part of balanced in is that i no longer have to consider high gain for either my HD600, T50rpIII or K712.

@jawbfl
 
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Oh yeah. To my ears, soundstage width is a bit greater and the noise floor seems to be lower. The soundstage being wider could be a symptom of a lower noise floor with balanced input. The best part of balanced in is that i no longer have to consider high gain for either my HD600, T50rpIII or K712.

@jawbfl
Thanks, in theory the signal from DAC to Amp is low so very prune to noise thus balanced inputs should be better, but I don't believe an amp can affect sound stage, as you said might be a side-effect of something else.
As long as RCA can output balanced then it's fine for a temporary setup till I get a decent DAC.
 

zepplock

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Oh yeah. To my ears, soundstage width is a bit greater and the noise floor seems to be lower. The soundstage being wider could be a symptom of a lower noise floor with balanced input. The best part of balanced in is that i no longer have to consider high gain for either my HD600, T50rpIII or K712.

@jawbfl
From charts, it has ~150db noise floor. How can you hear that? Not picking on you or anything, just wondering if I can reproduce it on my setup.
 

JohnYang1997

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From charts, it has ~150db noise floor. How can you hear that? Not picking on you or anything, just wondering if I can reproduce it on my setup.
It's actually the opposite. Balanced output has much higher output noise. The slightly excessive high frequency energy causes illusion of wider sound stage.
 

raistlin65

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From charts, it has ~150db noise floor. How can you hear that? Not picking on you or anything, just wondering if I can reproduce it on my setup.
And here are measurements Amir took with unbalanced input and output. SINAD 118db.
https://www.audiosciencereview.com/...sdrop-thx-aaa-789-amp.5001/page-4#post-111966

Seems highly unlikely there should be an audible difference between single-ended and balanced, unless someone has very difficult to drive headphones and listens very loud and is simply reaching the limits of the amp.
 

bequietjk

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THD and SINAD numbers look great for unbalanced in comparison to balanced input. Could this be because of higher voltage?

The lower frequencies look to be much more tamed and smoothed in balanced input vs that of unbalanced input.
 

raistlin65

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THD and SINAD numbers look great for unbalanced in comparison to balanced input. Could this be because of higher voltage?

The lower frequencies look to be much more tamed and smoothed in balanced input vs that of unbalanced input.
Not sure what you mean. Balanced or single-ended with unbalanced input, the 789 measures so well that any audible differences you find are most likely due to perceptual bias.
 

bequietjk

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@JohnYang1997 Right right. Just wanted to be clear that the topic was in regards to switching between the inputs and not the output.

For a frame of reference my listening chain goes:

PC > Motu M2 (balanced TRS - XLR out) > (balanced input) THX 789 (balanced output) > HD600
 

bequietjk

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@raistlin65 Perhaps :)

I'm only one owner thus can only speak for myself.

I wonder what other 789 owners have experienced.

@jawbfl It is also possible that my Motu M2 balanced output has better measurements than its unbalanced so in this regard, please take my comment with a grain of salt!
 
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zepplock

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@raistlin65 Perhaps :)

I'm only one owner thus can only speak for myself.

I wonder what other 789 owners have experienced.

@jawbfl It is also possible that my Motu M2 balanced output has better measurements than its unbalanced so in this regard, please take my comment with a grain of salt!
I have 789 and use it with both inputs with my He560. Those are hungry and with non-balanced input, I have to crank the volume knob up more, but still staying in gain II setting.
 

raistlin65

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@raistlin65 Perhaps :)

I'm only one owner thus can only speak for myself.

I wonder what other 789 owners have experienced.

@jawbfl It is also possible that my Motu M2 balanced output has better measurements than its unbalanced so in this regard, please take my comment with a grain of salt!
I'm waiting on drop to ship mine.

But a main reason I went with the 789 is because Amir's measurements show it to easily be noise and distortion free, regardless of how one uses it.
 
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