I have not noticed any difference between unity gain and pass through with home theater. So I would not quibble over the difference, either is fine as far as I am concerned.
I had a BAT and a Cary. The Cary was decent, but actually sounded a bit better direct from DAC. Don't buy anything from Cary anyway, they have the worst customer service and will flat out lie in your face.
The BAT was just a bad fit in my system. I am probably one of the very few that actually had my soundstage shrink.
Both of the above had either pass through or unity gain.
I am currently using a Levinson 523 preamp, quite a bit more than the Cary was, not a tube pre, but it is exceptional if you have the budget for it.
Another possibility if you have a turntable is the Manley Steelhead with a Skipjack for source swapping. Or maybe just get the Skipjack