MrDoud is correct. The comp out signal is affected by the volume control.
Personally, I like this as you can adjust for using the amp as a monitor and still get the comp out volume you need by working the board slider for volume on the channel the comp out is plugged in to, along with the amp's volume control.
Works for me, anyway.
How ya' doing Mr. Doud? The other guitar player from our band is in Paris right now, that lucky guy!
I told him that if he met Alizée, to tell her from me that she is "tres belle".