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

+1 for 100%

Only digital components meant to drive a power amp directly (no preamp needed) have a volume control.

In most cases that digital volume control is cheap trash. The more you turn it down the worse it sounds, hence the advice to keep it at full volume all the time so it’s essentially not being used (remember these are attenuators, so the more they attenuate the sound the more impact on sound quality they have).

The downside of keeping the VC at 100% when you do use a pre is that these components have a LOT of gain because, well, they’re designed to work without a pre! So, as you’ve observed, you need to turn your pre’s volume way down compared to other sources.

If you’re going to use a good pre, which is highly recommended, then you’re going to control volume at the pre, so that upstream VCs are not needed; so, digital components that have one should be avoided.

Good thing the senile dutchman revealed to Audiophiles that doubling the input voltage could cause clipping. Who wudda thunk?

It is possible to have lossless digital gain control. Audio DAWs use 32 bit floating point signal processing to achieve this when mixing.

Most definitely, but this thread is about budget digital and YouTube videos.

We already have 

BTW: absent serious but rare impedance mismatches all that a pre adds is more distortion/ colouring.

It sounds like your experience may be limited to budget preamps. I would advise auditioning high-end units. An excellent, thoughtfully chosen pre that synergizes well with your system has infinitely more impact on sound quality than $20,000 worth of tweaks.

There are two things here. 

1. DACs capable of directly driving power amps obviously incorporate some kind of line stage (preamp) circuitry, allowing them to output the voltage required to do so. Without it, they wouldn't be able to drive a power amp any more than a turntable or a CD player can.

Obviously, the quality of that preamp section will vary from one DAC to another.

2. The position that preamps are obsolete and do nothing other than creating distortions is commonly shared amongst SINAD fanboys on ASR.

Audiophiles, however, almost universally agree that a high-end pre is an indispensable part of a well-thought out system.

If my limited experience in the matter is worth anything, I drove my monoblock amps with a DAC for several weeks while I was refurbishing my Krell pre. When the pre was returned to service, and the DAC moved behind it where it belongs, the sound quality improvement was very much significant.

I'm in the camp of those who believe that a great pre is a necessity. I also believe that a system's sound signature should be determined by the pre + amps + speakers system core, and that digital sources have no role to play in it. Just be neutral. You know what they say about too many cooks in the kitchen.

@lanx0003 

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.

Sound quality notwithstanding, I have analog sources I need to switch, and I prefer discrete components performing single functions in my system; and finally, with very few exceptions, the best preamps are separates.

So, while a separate preamp makes the most sense for my own use case, that’s all preferences and there is no right or wrong answer.

Now I am sure some DACs are equipped with decent preamp stages, and I certainly don’t know every one of them, but I am going to have difficulty accepting that the vast majority of them are in the same league as high-end separates.

Finally, 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. Neither is a $15 Blue Velvet, by the way, despite the fact that those are original equipment in so many almost-high-end preamps selling for $2000 or $3000 or even more 

@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.