Its still ruining the sound merely having the thing in the same room.
With due respect, I suggest that musical enjoyment is not ruined by an AVR but rather by this type of attitude.
Besides, it's pretty easy. There are great preamps with HT bypass as mentioned above.
My gear doesn't have that, but it does have balanced XLR outs - I use a preamp and a separate HT pre/pro (no amp stage). I built a Neutrik connector patch bay and it works perfectly well and is basically the same as throwing a switch, probably better. Amps get the signal from the patch bay to their XLR inputs.
The patch bay does more than this too - you can switch signals to different amps, easily patch in a piece of visitor gear, or whatever. But of course that makes my listening room look more like a pro audio studio than a Temple to Sound.