Tweater hiss

The fact that you isolated your amp from the rest of the system would narrow it down to a couple of possible explanations that I would check first.
1. The noise is typical of the unit (ask Bryston)
2. Try an AC line conditioner. (garbage in - garbage out)
3. If not 1 or 2, I would be asking someone smarter than myself.

Kr4 that is exactly what I thought. I was expecting that once I disconected the preamp, the hiss would go away since it increased when I turnded the volume up. I have a Audio Matrix power conditioner coming on Friday so maybe this will help. I am also having a dedicated line put in soon as well. I will contact Bryston about it as well.

How much hiss is there? Can you hear it when you are more than a foot from the tweeter? If not, it's probably OK. Otherwise, see what Bryston says.

I listend again last night and the hiss can be heard about one foot away but not more than that. The volume increase is minimal when the volume is increased on the preamp. My guess is it coming from the amp. I will put on the power conditioner and see if that helps. Thanks for the information and help.

I installed the Audio Magic power conditioner and this reduced the hiss. Also greatly improved the sonic clearity of the music. I will wait to hear from Bryston on the amount of hiss that is normal. Thanks for your help.