My 4B-ST runs Hot

My experience with the 4BST is that it doesn't get so hot that you can't keep your hand over it. What kind of cables are you running to the speakers? High capacitance cables succh as the "Goertz MI" series can cause the amp to run hot (in my experience).

My 4B-ST runs warm, but not hot to the point it's uncomfortable to keep your hand on the lid -- even when driven hard. Is your amp getting sufficient ventilation? If it's in a cabinet or has less than 3-4 inches on all sides, you may need to provide it more space, or install a small fan (there are some very quiet types made for audio installations).

Four inches above the amp, open all around. Rack is Lovan. I use Audioquest Lapis ICs and Audioquest Sterling speaker cable--terminated for bi-wire at store. I must add that the heat seems concentrated on the right side of the top lid (if you are looking straight at the amp). The cooling fins on the sides of the amp are always warm, but not uncomfortably hot. However, the sound does not suffer at all, in fact at first I attributed the heat to normal amp life. I always turn my amp off after a listening session, so I don't know about the temperature when the amp is not that active. I don't know if there is something wrong with the amp that will crop up in the future. I wanted to bounce all this off everyone here first before I start shipping it back to Bryston.