I do not have first hand knowledge in this, but I agree with Karls. I once emailed Bryston and asked about bridging two 4Bst amps. They said bridging is not a problem. However, running a higher powered stereo bryston amp (the 14Bst)or two 7Bst's would result in better imaging and soundstage. Based on this advice from the manufacturer, one 4Bst would sound better than two bridged 3Bst's.
Bridging Bryston 3B-STs a few questions
I have one 3B-ST and am looking to add another 3B-St to drive my Thiel 3.6s... Has anyone had any problems bridging these amps or any negative experiences bridging any other amps that might apply to my situation? Any good results alternatively? Are there any problem with ground loops? Hum? Should I get two dedicated 20 amp lines or will one suffice? Some music (hip hop of my son's choice) can dim the lights in my house on peaks with one 3B-ST already. Nothing I listen to has done this however.