Although I once had a 4BST I sold it in favor of another amp & currently use an Ayre V-5x. I have a 508.20 but it is modded, so you may get results that are in the same ballpark that I have and that is with the VR4 GenIII SE's. I have the Gen III's but having heard the SE's I think they would do an excellent job with your gear.
BTW my dealer sells Bryston and VR. click here
BTW my dealer sells Bryston and VR. click here