DAC having remote volume control installed between...

[petercapo]

I have a tube preamp I really like that does not have a remote volume control.

Any reason why I should not connect a DAC (that has a remote volume control) between my high-level sources and my tube preamp? This would, of course, be to add remote volume control to my setup.

The high-level input impedance of my tube preamp is about 80KΩ. The DAC specs I have seen thus far indicate that their output impedance is pretty low. Though I suppose it depends on where the DAC's volume control is in its output circuit. If the DAC's volume control sits right at the DAC's output, then its output impedance would vary with the position of the volume control, correct?

But assuming any particular DAC's output impedance does not significantly vary with the position of its volume control, shouldn't this arrangement (high-level sources --> DAC w/remote volume control --> tube preamp without remote volume control) work well?

What do you think?

Thanks.
Peter

 

[staticV3]

Hi @petercapo! Welcome aboard.

shouldn't this arrangement (high-level sources --> DAC w/remote volume control --> tube preamp without remote volume control) work well?

One issue you may encounter is that DACs don't have analog inputs.
If your High-Level sources are analog, then you can't plug them into a DAC.

Instead, you'd have to get a preamp.

 

[petercapo]

Thanks for your reply. Actually, one or two of the current Benchmark DACs have analog line-level inputs. It must just route the analog sources through its own analog output section. It can toggle through its own inputs, whether digital or analog.

I guess my question is how a remote volume control built into a DAC works, though I suppose it may not be possible to generalize.

But I notice that the spec for the output impedance of the Benchmark DAC I am looking at is given as a single figure, with no indication that it varies with the position of the volume control. If it does have a constant output impedance, then I *think* my idea might work.

 

[staticV3]

Actually, one or two of the current Benchmark DACs have analog line-level inputs.

Those aren't connected to the DAC afaik. Just external inputs to the Benchmark's built-in Preamp.

Same deal as with the FiiO K5/K7/K9 for example.

I guess my question is how a remote volume control built into a DAC works

With a regular DAC that doesn't have analog inputs, the remote control controls the digital attenuation feature built into the DAC chip. So the volume attenuation is applied before the D->A conversion.

If the device has both analog inputs and remote-controlled volume, then this is typically done in one of two ways:
-either a fully analog signal path with a stepped attenuator between input and output
-or a a digitized signal path. Basically: analog in->ADC->volume control->DAC->analog out.