The HT Bypass, a $50 option on any new AVA preamp, is really simple to understand and use.
The bypass just switches whatever input source is selected directly to the output jacks, bypassing all controls and the line stage.
So you would connect the left and right main audio outputs from your HT processor to any set of line inputs on the T8+ for example, (there are six pairs of line inputs, tape inputs, tape outputs, and two sets of parallel line outputs).
Then in the normal position, the T8+ volume and balance controls and line circuits would command the system and drive the associated power amplifier. In the bypass mode, the HT processor would directly drive the power amp straight through the preamp and control the volume. No need for doubling up on cables or an external switchbox. No need to even have the preamp turned on to use the bypass mode, unless you have the unity gain buffered tape option, which is in circuit for the HT Bypass mode too if installed.
Call me at 651-330-9871 if you need more help with your HT setup.
Frank Van Alstine