Subwoofer with XP-22 in unity gain

The danger in that is you switch inputs to another line level source and your volume stays at 89. 

@goleksiak, the 89db setting is just telling the user where on the volume scale is 0db, i.e. no gain or attenuation.  Also, if you set input 1 at 89, all other inputs by default will be set at 89. This could be a recipe for disaster.  Why not use the Home Theatre pass thru on input 5??

@testpilot My DAC only has balanced outputs & Input 5 is single-ended. 

@audphile1 if system volume is set to 89 (0db gain) then what is the harm in switching to another line level input (say a phono)? 

Switching inputs on XP-22 maintains the previously set volume level.
If you have a digital source playing at that time you will pump that signal thru at 89 on volume scale when you switch to that input.
I hope that’s clear enough. What that means is a unity gain signal burst thru your entire system. What will be the outcome of this? Potentially fried component or speaker driver, including temporary damage to your underwear.

Use bypass for your AVR and don’t screw around. You will potentially learn a painful and expensive lesson otherwise. It is bound to happen.