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DAC as a preamp?

I need a new DAC. I use my computer for volume control, but do not trust it. I want separate volume control. The 90s me would have immediately thought preamp. But since I need a new DAC, my question stands ... DAC as a preamp?
I've posted more info about my system below.
I need some advice on the best way to go about getting volume control for these powerful asp1000 amplifiers. I've read about the high input impedance. I use a computer for my source playing Flac, wav or hi-res audio files. I'm using a very simple dongle Style USB DAC that sounds okay. I have choices, but do not know what my best bet is. For simplicity, it would seem I should just buy a better desktop DAC, such as and SMSL M500 and use the volume control knob on front. Or ANY other DAC with a volume control for that matter. I know I can use my volume control the USB. Provides through the keyboard on my computer. But with amplifiers this powerful, I figure I should have a volume control to prevent issues such as full volume noise blasts, which have happened before when the computer glitches. My second option would be to purchase a regular preamp. This would be the most expensive option, as I would want something at least as good as the Schitt Freya +, and that is $900! I would still need a decent DAC upgrade. This gets expensive with my health issues at hand. The last way I could go, is something like an all tube gain stage. I would still need a DAC, but a simple gain stage kit should only be a few hundred at most. The other two options I can think of, would be the pass B1 buffer clone kit preamp for 150 dollars, but I don't know if it would play nice with a high input impedance of the icepower amp. The most simple and cheapest route, would be be using the Sure digital volume control option. But I do not know how high fidelity that would be. I could really use some help. I've been out of this hobby for about 10 years now. I feel a bit lost and appreciate everyone who has helped so far.
flaxxer

Showing 8 responses by georgehifi

georgehifi's avatar
georgehifi
10,312 posts
 

unsound
@georgehifi, Would that in turn mitigate the interconnect capacitance concerns associated with passive analog volume controls, allowing for greater choices and useable lengths for interconnects?

Even if the analogue pot was on the output of the dac, if it were a 10kohm, which meets most needs, at the worst position it’s 2.7kohm output impedance.

This into 1mt of good interconnect which is at worst 100pF per foot is 300pF for the mt, in conjunction with that 2.7kohm pot at output impedance give a HF roll off of -3db at 196khz which as you can see is no problem.

Take it a step further, if the interconnect was 2mts long and poor quality at 200pF per ft then it’s still only -3db at 98khz!! still no problem at all.

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 

@georgehifi, would there be less impedance variability with a DAC’s digital volume control than through a typical passive analog volume control?


Yes the output impedance would remain constant and lower with a digital domain vc what ever the ss output buffers (opamps) impedance is, usually 100ohms or less.

Where with an analogue one if the vc is on the output after the output buffer (opamp), it would vary a bit, and if 10kohm in value, be suited better to amps with input impedances of 33kohm or higher.

If the analogue vc is before the output buffer it would then need more complex circuity, and an input buffer (opamp) as well, as the I/V stage or da chip would need it, the output impedance then would be constant and low as in the digital one. (but this way there is an extra (opamp) buffer in the signal path, I don’t like that)

The very best is what Wadia did with their flagship CDP’s and DAC’s, use a digital domain vc but with analogue stage gain setting links inside so you set the digital vc to be used in the top 25% of full volume into that system, so there’s no chance of "bit stripping" They state this in their setup user manulas that it's the best sound to go direct into poweramp, using this system

Cheers George


georgehifi's avatar
georgehifi
10,312 posts
 
I get a cleaner, less cluttered sound than I had with my Audible Illusions 3b tube preamp in the signal path.

I'll always agree with that.
One of the few later ones that are analogue domain volume controlled.
I prefer this "only if" there’s a chance of "bit stripping" with a digital domain one then, (still not called a preamp) more like an internal passive.
That’s why the $49 Schiit Sys is great to have, just in case the digital domain volume is too low (<70% of full) and could be "bit stripping"

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
But I only need to attenuate my volume. Not increase it.
So all you need is an attenuator.
Not more gain/distortion/colouration that an active preamplifier gives.

If you have a digital volume control in a dac, all that does is attenuate the dacs full max level. Which is what your after.

Or if the dac only has a fixed max level (no digital volume), then all you need is a passive attenuator like a $49 Schiit Sys passive. 
https://www.schiit.com/products/sys

Cheers George 
georgehifi's avatar
georgehifi
10,312 posts
 
Generally, preamp mode on a standalone DAC "is an afterthought".

sorry to confuse you

No confusion, "an after thought" infers something has been tacked on, this is not the case with dacs digital domain volume controls.
As the digital digital volume option in dacs is either there or it isn’t.
If it’s there it can be activated or not and left at full output. Sorry but nothing gets "tacked on"

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
Generally, preamp mode on a standalone DAC is an afterthought.
Sorry to correct you, there is no "preamp" in a dac it’s the same output stage, just that the volume is controlled in the digital domain before the D/A converter

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
So at that point, I tou may as well set your DAC volume to 100%, and just use the preamps volume again, lol
Nothing worse than not having a remote for volume.

The $49 Sys does not have remote control, I was saying to do it this way so you can still use the dac’s remote volume control.
Forest and trees?
http://corrimalregion.unitingchurch.org.au/wp-content/uploads/2018/10/image2.jpg
Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 


Low volume listening is usually not that great with a DAC direct to amp.

Simple fix
Most likely because it was "bit stripping" (lower resolution), for digital domain volume controls in dacs to give all bits (resolution), they need to be at or over 70% in volume, if this is too loud for you, simply insert a $49 Schiit Sys passive between the dac and poweramp.

Set the Sys volume control once only with the dac at 100% so you’ve got just over the loudest you’ll ever need, then back off the dacs digital volume, so then you’ll use it as the master volume in the top 1/3 of it’s volume range.

Cheers George
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