I have 2 OCM 500s of different generations or configurations as some may know David made these in several versions and in at least 2 generations. The newer one has a 17" black faceplate (I also once saw one in smokey silver), with BI-WIRE WBT binding posts (4 sets) and MOS-FETS. My 2nd one (I bought new) has a 19" faceplate with one stereo pair of WBT binding posts and Bi-Polar outputs instead of MOS-FETs and it had rack handles when I got it. Power was ALMOST doubled when bi-amped (500 up to 800 WPC @8 ohms).
I have been using them Bi-amped since I got the 2nd one nearly 20 years ago,
All OCMs were bi amp able as far as I know
I've had Levinsons, Krells, ARCs, Plinius and many others and these have no peers in my experience IMHO.....and BTW I've had a couple of phone convos with David and have always found him cordial and willing to give advice, etc.