BHK Pre volume click and sound change

[nortonkp]

Matching tubes, can sometimes be the culprit. That said, there are other causes as well. I’ve had both experiences.

BHK Preamp tube rolling

For what it’s worth, I’m noting the hiss/static issue I experienced with my BHK Pre below. Given the adjectives used above to describe these issues - thumping, pulsing, etc, tough to tell if it’s on point, but here it is anyway. When I added the BHK Pre to my system switching out the previous preamp, I noticed a distinct level of hiss coming from both speakers that was not there with the previous component. Same level of hiss from both, present when music was playing or not, and at a constant…