The reason, I suggested building a receiver on the 990 platform, is that Outlaw has tended to keep its receivers slightly below its top of the line pre/pro in terms of capability and sound quality.
Using that as a base assumption, it strikes me that the 990 is already physically built on a receiver frame. It certainly has been more stable the 970 and presumably is better musically as well. About all it is missing is a chip upgrade to support HDMI 1.3 input and possibly the new musical modes for Blu-Ray. I see that later as optional since the 990 already has 7 channels of analog input.
_________________________
Living Room 24x18 open 1/2 flight up to a raised dining room/hall 24x12
Outlaw 976 pre-pro running 5.1 system
Outlaw 750 for Artison Masterpiece LCR and 2 NHT SuperZeros rears
Velodyne Servo FX-1200
LG OLED65C8PUA via HDMI2 to/from 976 HDMI ARC
Roku Ultra
Samsung BD-D5500 BluRay
Amazon FireStick 4K to 976 Aux HDMI input for Amazon Music Ultra