Connecting a DAC directly to an amp?

" Absolutely insane why tubes in a great preamp like arc or many others, can’t be designed to allow shutdown during ht use. Sooooooo stupid. Sooooooo many users would love this. "

Really, if soooooo many users were clamoring for this don’t you think they would do it. The market for stereo preamps isn’t for home theater. Give it a rest

As with so many of such questions, the answer is: "It depends..." 

1) If the DAC uses digital means to volume control (bit stripping) it is of course possible - but particularly at lower volumes, the SQ is affected negatively.

2) If the DAC volume control is of top quality *analogue* design (and how many actually are?), it becomes a question of how much better a/any preamp's volume control AND overall design implementation is.

Starting with a very clean powersupply, a volume control (not really by potentiometers), sealed relay source switching, plus a separate or well screaned power supply etc.

3) If such a preamp is used, the general finding is, that the inclusion of such, using reasonable good IC's connecting the lot, the result in the cases I know of, including my own, will result in higher SQ.
M. 🇿🇦 

I run my Monarchy NM24 direct to the LTA Z10 amp; sounds better than with an additional pre-amp.

I experienced big improvement in SQ when my Teac NT-505 was connected to Modwright LS-100 preamp rather than straight to the amp connection. 

Modwright looks good.
Can tubes be off during ht bypass?
thanks

just read in manual that ht input can only be enabled via front panel and not remote.  Seems really odd.