Dunno why the 'video' input on the PV10 didn't work for you. Any line-level input should do as long as you set the gain appropriately. Better would be a preamp with a HT bypass input........
If you ran the HT pre out into your tube pre, you'd probably have to crank the volume high on the receiver to get sufficient volume from your tube preamplifier. But the way you had it, you were still going through the HT receiver's internal processing, which is less than great.
If you have direct, multi-channel (6- to 8-channel) inputs on your receiver, you can hook stereo analog sources into your tube preamp. Then run the main tube pre outputs into the left and right main direct multi-channel inputs on the receiver. You don't need to use all the channels. That configuration worked very well in my system and it avoids putting the signal through the receiver's internal processor. You'll have to experiment with where to set the preamp volume to get good output through the receiver volume. Then, you can either use the amps built into the receiver or take the L and R preamp outputs from the receiver and run them into your stereo amp. That setup should work fine.
My 6-channel inputs run through the volume control on my receiver but some receivers may bypass the volume control in the direct mode (usually not), but start with the volume set low on the tube preamp until you know if you are going through your receiver's volume control or not.
And you can still run a digital output from your CD player into the HT receiver (analog too, if you want), or run your analog CD/DVD outputs- through the tube pre.
For surround, just take the front left/right channel outputs from your home theater receiver and plug them into a line level input on your tubed preamp.
The volume control on the preamp has to be set at some mid position (typically 12 o'clock) and set to the same position every time you use your home theater receiver. Pick a spot on the preamps volume knob that is easy to remember and then use the test tone function on your home theater receiver to set your home theater speaker levels. To control the volume when using your home theater system just use the receivers remote.
I have the pre outs from my Denon AVR-4802 receiver feeding my Blue Circle BC3 tubed preamp. I also use my Denon DVD/CD player as a transport with a digital connection to the receiver and my digital cable box (40 music channels) is also connected to my receiver.
My turntable is connected to another of the BC3's line level inputs. The preamp is connected directly to my 2 channel Simaudio amp. The front speakers are also connected to the 2 channel amp's speaker outputs. When I want to listen to 2 channel music the home theater system is powered down and out of the loop.
Works like a charm...hope this info helps you in getting your system dialed in!