So you have a great hi end stereo preamp, but

I have a stereo pre-amp & a HT Receiver with line level outputs.

HT L/R outputs feed an input on the stereo preamp. Set stereo to fixed volume (80 dB) for HT use. Calibrate HT at that level, adjust theater volume with HT Receiver.

@decooney 

Same question opened in different threads over and over, looks familiar:
https://forum.audiogon.com/discussions/hi-end-tube-preamps-it-s-all-about-functionality

as i said in an earlier post, this is the new village idiot with megaphone in hand, same blather and nonsense over and over again

You hurt my feelings.  Time for some uplifting Barry Manilow youtube vids from my amazing ht system.

@millercarbon

"Oh, he can. For sure. Probably does. So what? Its still ruining the sound merely having the thing in the same room. People probably think I’m kidding, or exaggerating. I am not. I tried all this stuff, and with much better processors than any avr! HT is a wasteland. Guaranteed to bring down any system, any price, even just being in the room and turned on. Not even necessary to connect it to anything. Its that bad."

Nonsense.

There's plenty of products known to improve sound merely being plugged into an outlet. So we know for a fact things plugged in can affect the sound quality of other things that are plugged in. You seem to think this is a one-way street. That things connected to the grid cannot harm sound quality.

Nonsense.