I have a Black Ice tube DAC (new purchase, very happy) playing through a Raven integrated tube amp. Sounds really good, starting to rival my analogue front end.
It has a gain control, which doubles as a volume control for headphones. It is not designed to be connected directly to a power amp as far as I know.
I went with a Tube DAC with the intention of tube rolling, which I did immediately. Huge change after adding some NOS Mullard’s. Done for now.
No reason not to use a Tube DAC with a SS amp. Or the converse...my phono stage is SS. IMO the Cart/TT does the sound shaping and I wanted a clean, quiet transfer from the PS.