HT Pre/Pro 7.2 Upgrade???

I have a good friend that is using a B&K Reference 50 in his 7.2 home theatre system. He's owned the Ref 50 since new and is very partial to it. I'm trying to convince him to upgrade and make the move but we are having trouble figuring out what to upgrade to. 

Some of the requirements are as follows:

• 7.2 channel capable
• HDMI 
• black in color
• comparable or better in sound to the Ref 50
• must have a remote
• prefer used as the price is typically better
• removable power cord (IEC plug)

If I think of anything else I'll add to it. 

His current system includes Oppo 105, B&K Ref 50, 2 Carver TFM-55x amps, 1 Carver A753X, Martin Logan Odyssey (mains), Martin Logan SL3 (side surround), Martin Logan Aires I (surrounds), and Martin Logan Theatre (center). 

What would you all recommend for this application?