Topping D90 Balanced USB DAC Review

[curiouspeter]

Or the A90, It's cheaper and apart from volume control looks to have all the exact same specs, which leads one to believe that it has much of the same moving (not moving) parts.

I doubt either has USB volume control. This means Roon Device Volume cannot be used.

 

[nimar]

I doubt either has USB volume control. This means Roon Device Volume cannot be used.

I'd be pretty impressed with Topping if the A90/Pre90 had usb volume control, considering they don't have any usb inputs.

Not sure why this is relevant, I'm fine with volume being fixed in Roon and controlling it at the dac/preamp. That said, using Roon is another reason why the a90 is a great preamp, I use auto levelling in Roon to -14LUFS so don't need to change volume between albums.

 

[Tokyo_John]

Or the A90, It's cheaper and apart from volume control looks to have all the exact same specs, which leads one to believe that it has much of the same moving (not moving) parts.

It also looks like they both have 20/40 ohm preamp output impedance. I’d like to know more about the practical differences...is it really only the volume adjustment/remote (and optional input selector/attachment) that is different?

 

[nimar]

It also looks like they both have 20/40 ohm preamp output impedance. I’d like to know more about the practical differences...is it really only the volume adjustment/remote (and optional input selector/attachment) that is different?

Pretty much all the specs are identical, with some very minor differences (16db vs 15.5db max output etc). Technically the Pre90's volume implementation could lead to lower cross talk but the a90 is already so good that who cares. Not to mention that you get a very good HP amp with the a90. I get why Topping produced the Pre90, and it's wonderfully done. I (and I suspect many) just don't have a real use case for it (needing more than 1 balanced input) and am perfectly happy with the DAC/a90 combo for both headphone / speaker listening.

 

[Harmonie]

I imagine the effect of the digital attenuator would be similar to running back up the IMD curve by the same number of dB. I.e if you set -20dB digital atten then that is the same as running the DAC with a -20dB signal. So your 120dB SINAD DAC becomes a 100dB DAC. Not too much of an issue if you have a 4V O/P DAC feeding a 4V sensitivity mono block this will will nicely scale. In fact you might wish to have the capability to overdrive the power amp by a dB or two so that you can reduce volume by a dB or two to allow for inter sample overs. A problem arises if you feed the DAC into a much more sensitive amp then you end up throwing away dynamic range. Topping’s answer buy the PRE90

I'm convinced now that a preamp of any kind will help my D90 combined my sensitivity spec'd 0,775v mono amp.

The missing thing on the a90 for a lazy slob like me is the remote

Question is pre90 or A90 ?
I need that remote too.

 

[Harmonie]

Pretty much all the specs are identical, with some very minor differences (16db vs 15.5db max output etc). Technically the Pre90's volume implementation could lead to lower cross talk but the a90 is already so good that who cares. Not to mention that you get a very good HP amp with the a90. I get why Topping produced the Pre90, and it's wonderfully done. I (and I suspect many) just don't have a real use case for it (needing more than 1 balanced input) and am perfectly happy with the DAC/a90 combo for both headphone / speaker listening.

For sure.
But when you listening via your speakers,
do you use the D90 variable output enjoying the remote control (within a very reduced range) or at 0db and use the A90 volume?

 

[nimar]

For sure.
But when you listening via your speakers,
do you use the D90 variable output enjoying the remote control (within a very reduced range) or at 0db and use the A90 volume?

I think I said above, 95% I have the D90 at 0db and the a90 at my preferred level, usually only my wife turns the d90 down via the remote. Sometimes I turn the a90 up, but its rare enough that its ok to get up.

On a related note, I was digging into the a90 figures some more and working out real Vrms outputs and posted https://www.audiosciencereview.com/...ne-amplifier-review.13592/page-98#post-720142 but seems that thread is much quieter than this.

 

[Harmonie]

I think I said above, 95% I have the D90 at 0db and the a90 at my preferred level, usually only my wife turns the d90 down via the remote. Sometimes I turn the a90 up, but its rare enough that its ok to get up.

On a related note, I was digging into the a90 figures some more and working out real Vrms outputs and posted https://www.audiosciencereview.com/...ne-amplifier-review.13592/page-98#post-720142 but seems that thread is much quieter than this.

Good point.
While D90 fixed volume = D90 variable output at 0db. There is a big advantage, using the D90 at variable output keeping it most of the time at 0db and adjusting via A90..
Nevertheless, from CD to CD, track to track or just different ambiance, you do NEED a volume adjustment.
The remote becomes mandatory when you are 9 feet away (nowadays at least).

So Pre90 or A90

 

[nimar]

Could save me some typing by reading up . I use auto levelling in Roon, so everything is -14 LUFS and thus the volume is 95% of the time exactly where it should be.

 

[Harmonie]

Could save me some typing by reading up . I use auto levelling in Roon, so everything is -14 LUFS and thus the volume is 95% of the time exactly where it should be.

Sorry for giving you all that trouble, but so many threads and this one alone has over 3000 posts !

But thanks for your answer.
I'm still at square near to 1:
Pre90 or A90 ?

I may order both and return one ? I hate doing so though.

 

[mocenigo]

I'm convinced now that a preamp of any kind will help my D90 combined my sensitivity spec'd 0,775v mono amp.

What about inline attenuators?

 

[Harmonie]

You mean the -10, 15db aso in RCA or XLR form ?
Not sure, I think I need a bigger range.
I noted that with my D90 <> mono's I could vary it's output from 0db to -27db or so (on the D90 volume pot). depends on the record.
I have some tracks which can accept the 0db Patricia Barber, A Distortion Of Love ...

 

[pLudio]

Nevertheless, from CD to CD, track to track or just different ambiance, you do NEED a volume adjustment.

ReplayGain

 

[Harmonie]

ReplayGain

How do you do that with a CD transport ?

 

[Tokyo_John]

I imagine the effect of the digital attenuator would be similar to running back up the IMD curve by the same number of dB. I.e if you set -20dB digital atten then that is the same as running the DAC with a -20dB signal. So your 120dB SINAD DAC becomes a 100dB DAC. Not too much of an issue if you have a 4V O/P DAC feeding a 4V sensitivity mono block this will will nicely scale. In fact you might wish to have the capability to overdrive the power amp by a dB or two so that you can reduce volume by a dB or two to allow for inter sample overs. A problem arises if you feed the DAC into a much more sensitive amp then you end up throwing away dynamic range. Topping’s answer buy the PRE90

Does the SINAD floor remain at the same absolute level after digital attenuation? Is the floor fixed at the same level even as attenuation of the data stream is applied? If so, then the above statement is true, a -20dB attenuation would decrease dynamic range of a 120 dB signal to 100dB.

On the other hand, if the SINAD floor changes as attenuation is applied, then -20dB attenuation will not produce a -20dB drop in dynamic range. It could either be worse...or better...depending on whether the floor rises...or drops.

 

[nimar]

Does the SINAD floor remain at the same absolute level after digital attenuation? Is the floor fixed at the same level even as attenuation of the data stream is applied? If so, then the above statement is true, a -20dB attenuation would decrease dynamic range of a 120 dB signal to 100dB.

On the other hand, if the SINAD floor changes as attenuation is applied, then -20dB attenuation will not produce a -20dB drop in dynamic range. It could either be worse...or better...depending on whether the floor rises...or drops.

With digital attenuation noise is constant, so a reduction of signal decreases SINAD. Which is why when people claim all you need is ~85dB because anything better is inaudible they are missing the point. Its not perfectly linear but lets say its close enough to pretend it is. When you start at 120dB at 4Vrms, and turn the volume down to -30db on the DAC, you still have 90dB SINAD, above audibility, But if you DAC started at 100dB, you then get into the realm of audible issues.

With analogue attenuation noise is also reduced.

 

[Nicolaas]

Does the SINAD floor remain at the same absolute level after digital attenuation? Is the floor fixed at the same level even as attenuation of the data stream is applied? If so, then the above statement is true, a -20dB attenuation would decrease dynamic range of a 120 dB signal to 100dB.

On the other hand, if the SINAD floor changes as attenuation is applied, then -20dB attenuation will not produce a -20dB drop in dynamic range. It could either be worse...or better...depending on whether the floor rises...or drops.

Exactly, so why not measure SINAD at for instance -20, -30 and -40 dB of digital attenuation. Unless scientists overhere are 100 % sure about the results in advance...If not, the guessing continues! And it probably will because the idea lives that there are great and crappy digital attenuators...

 

[nimar]

Exactly, so why not measure SINAD at for instance -20, -30 and -40 dB of digital attenuation. Unless scientists overhere are 100 % sure about the results in advance...If not, the guessing continues! And it probably will because the idea lives that there are great and crappy digital attenuators...

You want to know the max spec, what the device is capable of and it directly correlates to how it will perform at -20, -30 etc. Who's to say how loud people choose to listen at, 4Vrms is a constant that can be agreed upon. Amir even reduces DAC's to 4Vrms that output higher than that to keep the constant.

These days digital attenuation is handled by the DAC chip itself and thus hard to screw up, 99% are done with 32bit precision and not worth worrying about.

 

[Nicolaas]

You want to know the max spec, what the device is capable of and it directly correlates to how it will perform at -20, -30 etc. Who's to say how loud people choose to listen at, 4Vrms is a constant that can be agreed upon. Amir even reduces DAC's to 4Vrms that output higher than that to keep the constant.

These days digital attenuation is handled by the DAC chip itself and thus hard to screw up, 99% are done with 32bit precision and not worth worrying about.

Indeed hard to screw up, but maybe it is...

 

[Tokyo_John]

With digital attenuation noise is constant, so a reduction of signal decreases SINAD.

I can see noise being constant (assuming that dither noise is negligible, via noise-shaping, etc.). The SINAD floor includes both noise and harmonic distortion, so it is generally a question of THD as well, not just noise. Of course, if THD<<noise then this is irrelevant. This seems to be the case for the D90, according to Amir’s measurements. (-130dB THD compared to -120dB SINAD).

Which is why when people claim all you need is ~85dB because anything better is inaudible they are missing the point. Its not perfectly linear but lets say its close enough to pretend it is. When you start at 120dB at 4Vrms, and turn the volume down to -30db on the DAC, you still have 90dB SINAD, above audibility, But if you DAC started at 100dB, you then get into the realm of audible issues.

Understood, thanks for spelling it out more clearly. And -30dB is anyways a lot of attenuation...if one has to go lower regularly, then a preamp or less muscular power amp is called for.