What's too hot? operating temp Bryston amp

Is 195 degrees (measured at the center of the heat sink next to the case) abnormally high for a Bryston 3B ST?

Temperature approximately same on both sides of amp

measured after about three continuous hours of loud listening

I am going to contact Bryston but Id like a more immediate response
God to the Bryston owners' site on AudioCircle. There have been threads on precisely this topic.
Great that you are showing an interest - those output MOSFET's do run very hot so I would not be worried. You may not be aware of this but typically your speakers see that temperature and more inside the VC of the drivers - which is why they make pro drivers with larger and vented voice coils and with tighter tolerances.
I have a pair of Brystin 7B ST's that I drove B&W 801's and 800 with. They always run cool. They only get warm to the touch.

Contact Bryston's technical department and get instructions on how to set the bias on the amps. If you are not running them hard they should not be that hot. If they are under warranty (most likely) Bryston wil probably set the bias for you.
I had a 9B-THX that ran hot, when pushed. I drove Martin logan's