High end stereo preamps? Worth it?

@mitch2,@emergingsoul

The only case where I could think of mismatch issues between DAC, attenuator and power amplifier are impedance related: low output impedance on the DAC, high impedance inputs on the power amp or very poor choice of interconnects. This is however an unusual constellation that one normally needn‘t be overly concerned about.
Where you do get a problem is when you rely on a DAC‘s digital attenuator; for the avoidance of doubt all digital output levels should be set to max. In other words: an analogue attenuator or volume control in the DAC is always needed

@mitch2 

I was obviously referring to analogue sources, not DAC outputs

This threat is unneccesarily long: assuming no highly unusual impedance miss match there is no conceivable reason for a separate preamp in a digital reproduction chain: additional cabling and circuits for no gain (pardon the pun)

@emergingsoul,

if you must have a preamp, look at a used Graaf 13.5b II. at least you‘ll have a balanced connection to the amp out of it. it still won‘t get you remote control, though.
i

@alfa100

my experience exactly with Antelope Zodiac Platinum +10m. If the phono preamp has enough gain even analogue sounds better through the Zodiac than the preamp.

Given high output voltages of modern DACs, the Pre becomes a glorified attenuator. The same result is achieved by either buying a DAC with analogue volume control or using a passive attenuator. There is really no good reason to use a Pre in digital playback. Analogue however is a different matter...

@djones51,

unfortunately a digital volume control progressively leads to a loss of resolution as the available bits get truncated. As long as you stay above say 80% of max volume, your statement applies; below, not so much