Connecting a DAC directly to an amp?

I connect Dave and HMS to Line Magnetic 508 pre input.

Thus I control the volume through Dave remote.

It is working well.

But I have Schitt Freya pre between Dave and my headhone  amps to connect 20 ft balanced cables.

I used to run my PS Audio DirectStream directly into my PS Audio M700's and it worked great. I've since then traded in my Stellar Amplifiers for a Balance Audio Technology VK50-SE feeding two Orchard Audio STARKRIMSON Amplifiers and two ICE Power ASP-1000 Amps inside a pair of KEF 105/3's.

The Preamp did make an improvement in overall soundstage/clarity but the DSSr. on it's is no slouch. People have paired it with the BHK Preamplifier and heard improvements.

YMMV

Have looked into a Barrett preamp $9k which shuts down tubes while doing ht bypass.  Barrett may be a great box and only 2 tubes and other fancy circuitry that avoids need for more tubes.  but more tubes would seem better.
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.

so I may have to live with more frequent tube changing and higher electricity costs to have a great tube preamp all ready to go at a moments notice.  

" 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. 🇿🇦