Do Audiophiles usually keep the gain of the digital source at around 80%?

@devinplombier One thing we can agree on, I think, is that whether standalone or integrated to an amp or to a DAC, a preamp or preamp stage is always involved.

The quality 'gain' stage (or buffer) in Harmony micro Dac I was referring to earlier is NOT a preamp section, rather a 'voltage' gain stage serving two purposes: increase of voltage to line level and impedance matching.  It does not have the volume control to be qualified as a preamp section.  However, it drives my amp pretty well.  The 32bit digital volume control from Wiim Ultra renders no resolution loss, transparent sounding even down to low level.

at the risk of being labeled a VC snob, I am going to have to respectfully push back against the notion that a digital volume control, even a 32-bit one, is an acceptable choice in any but value-conscious devices.

I wouldn't call it snobbery, but there's definitely prejudice involved. I did a simple comparison between the digital volume control on the WiiM Ultra and the 64-step relay analog volume control on the highly praised Schiit Saga 2. At normal listening levels (60–65 dBA), the sound quality was nearly indistinguishable—both were detailed and transparent. However, at lower volumes around 45 dBA, I actually preferred the digital volume control. It delivered articulate bass and clear treble, while the analog counterpart sounded a bit muddy. You might argue that the Saga 2 is only mid-end and that a high-end preamp would perform better. But that’s precisely the point of this comparison: I was able to get better sound at low volume from a device like the WiiM Ultra, which is priced similarly to the budget-friendly Saga 2—whereas achieving the same low-volume performance with an analog preamp might require spending significantly more ($$ or even $$$).  Note that the soundstage shrinks in both scenarios—there's no clear winner in either case.

If the dac has a proper quality attenuator rather than adjusting volume in the digital domain there is nothing to be gained from a pre unless it has digital input substituting for the entire analogue stage of the Dac. I have yet to hear a non impedance based argument to the contrary and impedance is a non issue in 90%+ of all cases

@sns - I'm afraid it's YOU who are incorrect. lanx00003 is correct. I owned an A8, and it DOES have a 'proper' analogue volume control circuit, and it's VERY good. I tried it direct into my Threshold S300, bypassing my Audio Research Reference 3, and it was almost as good, which was a great surprise. It was so good that I thought that the pre-amp in the (twice the price) A10 must be better, so I thought I may be able to ditch the Ref3 with a purchase of the beautiful (IMO) A10, so I bought one. It's still not as good overall as the Ref3, so it's staying.

dmann777 - You could try the A8 direct into your power-amp, but it would depend on how many sources you need to switch, to determine if that's an option for you.

You must set your A8 to volume pass through, so you are not using the pre inside it, as, if you do, you are now using TWO pre-amps in line with each other! = not a good idea. So set the A8 volume at 100% and deal with other issues. Maybe the -3db thing, which is easily implemented in the A8, will help, but using RCA may be the answer to reduce possibly overdriving your pre. There is, generally speaking, no sonic advantage to using XLR unless you need to use very long cables.

According to one video, it looks like there is a setting to disable the preamp section of the Eversolo.  This is what is needed to use the Mac pre.

@sns  - I’m afraid it’s YOU who are incorrect. @lanx0003 is correct. I owned an A8, and it DOES have a ’proper’ analogue volume control circuit, and it’s VERY good.

@daveteauk 

Well... Actually, the a8 has a digitally-controlled, relay-switched, resistor-ladder volume control. Here you can scroll to a hi-res view of said VC in situ.

It’s presumably controlled by an Arduino-like processor that also controls the OLED display and such. 

So, no, it’s not a ’proper’ analogue volume control circuit in the sense that when you turn the A8’s volume knob you’re still spinning a cheap digital encoder like a $99 Topping. Encoders have a deplorable feel that is out of place with gear with high-end pretensions.

BUT! Does that affect sound quality? Well, probably not, because as you otherwise correctly pointed out, components in the signal path are indeed analog (namely relays and SMT resistors).

There’s kind of a problem, though.

As the picture shows, Eversolo use an array of 16 relays to switch between resistor pairs. Relays are DPDT (double pole double throw), so each relay contains 4 discrete switches, operable in pairs. 16 x 4 = 64 volume positions, which does provide excellent granularity.

These relays are Omron G6K series, a common general- and industrial-purpose relay that costs about a buck in quantity. Its datasheet can be found here for your perusing pleasure.

G6K relays are coil-operated and have aluminum contacts. They generate EMI, unlike a proper mechanical resistor-array attenuator that doesn’t generate any because the switching is mechanical and the energy necessary to operate the switches is provided by your hand. Not to mention that mechanical attenuators impart a lovely, substantial feel to the volume control. Such things matter to some folks, including myself. 

Anyway, it’s not clear why anyone would want sixteen mechanical relays clicking in their signal path?

On the flip side, the cost of a real resistor-ladder attenuator can easily exceed the price of the entire Eversolo A8. So there’s that. 

In summary, the A8’s volume control is definitely a step above the usual $2 junk chip found in low-end chifi and AVRs from Costco, but it does not come close to analog state of the art.