Suggestions for a holographic preamp?

I don't know why he couldn't have put a 'Mute' button on there - all I really require is volume and mute. 

@larsman Many mute circuits have the potential to mess with the sound.

Since your amp has a balanced input you might consider a balanced preamp as well. If you do, its helpful if that preamp supports AES48, the balanced line standard. The standard helps prevent the interconnect cable from having a 'sound' (coloration). There are not many tube balanced preamps that support the standard. Many audiophiles don't realize how important that is; getting rid of cable interactions in the system opens up transparency which contributes to a more holographic sound stage. 

@atmasphere - Wow, thanks for all that great information! And yes, I was leaning towards a balance preamp as well, so it can take advantage of the balanced XLR output of my DAC.  

Is there some spec I should look for to see if it supports that standard? 

A Post follows that was made in 2019.

"  In his Positive Feedback review of the EAR-Yoshino 868L line stage pre, the reviewer made the statement that, though the 868 provides XLR jacks for balanced operation, the pre-amp circuitry itself is single-ended. Designer Tim deParavicini in his manufacturer reply corrected the reviewer, stating that no, the 868 is a true balanced design. It is a commonly-held understanding by audiophiles and semi-pro hi-fi reviewers that a true balanced amp by definition has doubled parts. As atmasphere just said, that is a misconception and misunderstanding of what balanced is. A pre-amp can have single-ended circuits yet be true balanced in operation.

The real concern in any piece of gear is how the balanced inputs/outputs are implemented. In the EAR 868, Paravicini accomplished that goal via transformers. In his Music Reference RM-200, Roger Modjeski does so with a resistor network. Companies with lower standards typically create balanced inputs/outputs with the dreaded opamp, and with the expected sonic compromise. A higher retail price does not necessarily buy one balanced ins and outs NOT created with opamps. If possible, inspect the schematic of any piece of balanced gear you are considering buying, to see how it’s balanced connections are created, and if they conform to AES48. " 

The Following is the Industry Info that can be investigated.

https://www.aes.org/publications/standards/search.cfm?docID=44

Aric Audio Motherlode...you should at the very least reach out to him.

@pindac - I checked out that link, and they've got those documents, but you've got to buy them. If it was electronics stuff, I wouldn't know what I was looking at anyway. 

I don't mind 'coloration' - I usually quite like it; I'm more interested in how the music makes me feel than how accurately it reproduces what the producer laid down. 

 @laaudionut - I might just do that; he might have some kind of solution to accomplish a remote muting functionality; I'm sure he's been asked about it before.