Time to ditch the preamp?

[LaLaLard]

I've been using my RME ADI-2 for about 2 month now.

Output impedance is 100ohm to RCA or 200ohm to Balanced.

Amps I'm using are Allusione Hypex NC500 Monoblocks. Their input impedance is about 50k. Can't find the data but that's what I remember from the seller.

I've heard some kind of principle that the input impedance of the power amp should be at least 20 times of the output impedance of the input device.

In this case it is good since even 20 times of the Balanced output is still less than 10% of the input impedance of the poweramps.

Does this mean as long as the impedance are a match, we no longer need Preamp in this kind of setup?

P.S. In terms of SQ I have been satisfied with this setup.

 

[restorer-john]

Does this mean as long as the impedance are a match, we no longer need Preamp in this kind of setup?

As long as the output swing in volts is sufficient to drive your amplifiers, all will be well.

Preamplifiers obviously offer a ton of inputs, filters and tone controls in addition, but if you don't need or use them, ditch the preamp.

 

[March Audio]

I've been using my RME ADI-2 for about 2 month now.

Output impedance is 100ohm to RCA or 200ohm to Balanced.

Amps I'm using are Allusione Hypex NC500 Monoblocks. Their input impedance is about 50k. Can't find the data but that's what I remember from the seller.

I've heard some kind of principle that the input impedance of the power amp should be at least 20 times of the output impedance of the input device.

In this case it is good since even 20 times of the Balanced output is still less than 10% of the input impedance of the poweramps.

Does this mean as long as the impedance are a match, we no longer need Preamp in this kind of setup?

P.S. In terms of SQ I have been satisfied with this setup.

Its absolutely fine. If you think about it a pre-amp might have a similar output impedance, so there is no difference, except that you have removed another source of distortion and noise from the chain. 50kohm load wont create any issues for the ADI

 

[Sal1950]

To refrain what's already been said,
The best preamp is no preamp.
So long as the impedance and drive voltage work.
In your case its A-OK

 

[LaLaLard]

thanks everyone. I always feel happy for ditching a particular device since I believe the less the better in Audio

 

[Willem]

To be precise, a DAC like the RME ADI-2 DAC is in fact a modern preamplifier. It delivers a signal that can be adjusted to match the input of any consumer or pro audio amplifier, and it allows you to set volume and to switch between sources. Only this time these sources are all digital. In addition, and unlike many such DACs, the RME ADI/2 DAC also has more traditional but very useful features such as bass and treble tone control, balance control, and even Yamaha style variable loudness. On top of that, and unlike traditional preamplifiers, it has (manual) parametric equalization with five filters.
Adding an analogue preamplifier to the chain is therefore like having two preamplifiers, one after the other. The only functionality that the RME does not have is an analogue input. Since my family insisted that I keep my Linn Sondek/SME 3009 turntable, I bought a PRO-JECT optical E box with a MM input and an optical output. Purists may be horrified, but I am convinced that even a mediocre ADC (butI don't know how good or bad the Optical E box is) will outperform vinyl resolution by a wide margin.

 

[JohnYang1997]

Does no one know that digital volume control doesn't attenuate noise?

 

[SIY]

So what? Run the numbers.

And neither do most preamp topologies, for what that's worth.

 

[March Audio]

Does no one know that digital volume control doesn't attenuate noise?

As has been pointed out before that is not a real world problem.

The noise level of a good dac even after amplification will be inaudible with all but the most sensitive (probably over 100dB/w/m) speakers. Most of us have speakers closer to 85dB/w/m.

Non issue.

 

[JohnYang1997]

So what? Run the numbers.

And neither do most preamp topologies, for what that's worth.

What's "most preamp topologies"?
If you meant most under standard poor designed preamps, yes that's true.
A simple preamp with opamps like opa1612 even in parallel with a 10kohm pot attenuates the signal as well as noise the same time.

 

[JohnYang1997]

As has been pointed out before that is not a real world problem.

The noise level of a good dac even after amplification will be inaudible with all but the most sensitive (probably over 100dB/w/m) speakers.

Non issue.

Not an issue doesn't mean it's better. Objective fact is good preamp is better. Unless the dac only has 200nV noise 20-20khz.

 

[SIY]

What's "most preamp topologies"?

Not doing something stupid like putting the volume control at the output.

A simple preamp with opamps like opa1612 even in parallel with a 10kohm pot attenuates the signal as well as noise the same time.

It does not attenuate the preamp's noise

 

[March Audio]

Not an issue doesn't mean it's better. Objective fact is good preamp is better. Unless the dac only has 200nV noise 20-20khz.

Yes it is better if the noise and distortion and colouration a pre amp adds is removed. Not to mention the channel imbalance problem a typical pre analogue volume pot will create.

If the noise is inaudible, its inaudible. Also don't forget that as you turn the volume down the power amp noise will start to dominate anyway.

 

[JohnYang1997]

Yes it is better if the noise and distortion and colouration a pre amp adds is removed. Not to mention the channel imbalance problem a typical pre analogue volume pot will create.

What colouration would it add? The performance of single 1612/1611 is far superior performance any dac in the world that I know.

 

[March Audio]

What colouration would it add? The performance of single 1612/1611 is far superior performance any dac in the world that I know.

You obviously haven't played with many pre amps. They aren't just an op amp.

A pre will add additional noise and distortion and channel balance problems

 

[JohnYang1997]

Not doing something stupid like putting the volume control at the output.


It does not attenuate the preamp's noise

The preamp with single 1611 will have lower noise than any dac that I know. Two in parallel will be even lower.

 

[JohnYang1997]

You obviously haven't played with many pre amps. They aren't usually just an op amp.

An pre will add additional noise and distortion.

Many preamps are shit that's true. Because those are sub standard. Good preamp on the other hand can attenuate noise and give better overall performance of the system.

 

[March Audio]

Many preamps are shit that's true. Because those are sub standard.

Good preamp on the other hand can attenuate noise and give better overall performance of the system.

And that's the point.

The best pre amps can be audibly transparent. However adding noise, distortion and imperfect channel balance does not improve the performance.

The noise part is not relevant if its so low its inaudible. As I mentioned, it's also only true until such point you reach the noise floor of the power amp which is usually a fair bit higher than the sources before it. So there is no point in talking about paralleling pre opamps if you what you are hearing is the power amp noise.

 

[JohnYang1997]

The best pre amps can be audibly transparent. Adding noise and distortion and imperfect balance does not improve the performance.

The noise part is not relevant if its so low its inaudible. As I mentioned, it's also only true until such point you reach the noise floor of the power amp which is usually a fair bit higher than the sources before it.

You don't want to forget the power amp amplifies the noise of the preamp stage.
let's say 25% volume from 2uV noise dac.
and power amp of gain of 30db/30times(close enough)
preamp can give 0.5uV * 30 = 15uV noise
dac itself will give 60uV
A top notch power amp can have under 30uV noise.
Yeah it's true that 60uV may not be audible. But objective speaking 20 something uV is lower.

 

[March Audio]

I'm not forgetting anything.

So yes, again inaudible is inaudible.

What's your point?

I would rather have correct channel balance and a volume control that doesn't wear, become noisy and control on the app on my tablet and phone.