Thanks. I missed the "specs" hyperlink.

One very interesting feature about that amp is a "pre-amp only" mode. When using pre-amp outs on a receiver, the signal can get distorted because the amp section is not disconnected. This distortion becomes significant at higher volumes and of course causes the external amp to amplify garbage.

I don't know if that mode works on a per channel-basis.

It also has per sub control.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated