Glad I saw your post the day after I put my Bryston 4B3 into my system as I would have otherwise started stressing about your issue. Just a note, had planned to biwire my Tannoy Cheviots with Analysis Plus Black Mesh Oval 9 gauge cable as I have a long run to one speaker, and found the Bryston posts only will accommodate one spade, so am going to have to wait to have each pair of cables reterminated into one on the amp end.
The Bryston sounded immediately better than my Parasound A23+ as soon as I turned it on and expect it will sound even better in 100 hours or so, sonInsuspect you will be happy either way you go. So far the bass sounds much tighter, and I am hearing more detail and greater instrument separation, including instruments I never noticed even in some old favorites that have become standards For auditioning new gear. Also, having played jazz and seen a lot of jazz live, I was happy to hear an improved gritty realness in saxophones mixed low as backing instruments that I thought my pre-upgraded system already handled pretty well.
If you somaettle on a Bryston, I hope you post on your thoughts on preamps as a new one is next on my list (have the Parasound Halo P6)