You had the right idea in the first place. The HT passthrough does just that. It passes the signal from the pre-pro directly on to the power, bypassing the preamp's own circuits. This allows the pre-pro to control the overall volume of everything, including the main left and right speakers. When you switch the preamp's selector over to another source, the preamp takes back over the main left and right channels. Of course, you'll want to mute or turn off the pre-pro when you switch the preamp to another source. Hope this helps.
As for a recommendation for a good preamp, I'm kind of partial to Audio Research myself. But there a lot of good ones out there. Good luck.
As for a recommendation for a good preamp, I'm kind of partial to Audio Research myself. But there a lot of good ones out there. Good luck.