What's causing hiss??

Does your PS Audio DAC have any type of gain settings? It could be internal or external. If it does, lower the gain and that will probably fix the problem.

I tried an experiment this morning. I sent the tube pre section out to my el cheapo but zero noise t-amp and the hiss went down considerably. T-amp is 15 watts, integrated is 150 watts, speakers are a super efficient 104 db Klipsch LaScala.

Was the hiss still too high to be acceptable?


Have you tried a different set of speakers with a lower sensitivity? If the hiss is still unacceptable with different speakers, then it would seem that there is a problem with the Vincent’s preamp. If the preamp does have a problem, then doing anything else makes no sense until it is repaired.

Mezmo makes a valid response about tubes, however the Vincent uses 3 tubes, one that is common to both channels.

"Have you tried a different set of speakers with a lower sensitivity? If the hiss is still unacceptable with different speakers, then it would seem that there is a problem with the Vincent’s preamp. If the preamp does have a problem, then doing anything else makes no sense until it is repaired."

I agree. If you have the means to try a less efficient pair of speakers, that would go a long way as to finding out the nature of the problem.

If you hear identical hiss in both channels, it's more likely capacitors on the amplifier side power supply. Checking/replacing preamp caps is also encouraged.
I would also replace/upgrade coupling caps that believe it or not also can go bad.
If the hiss is only to one channel, or heard substantially higher one channel vs. the other, than you can check/swap/replace tubes between both channels to ID the bad tube.

You should try a very quiet, low powered, tube amp with your Klipsch speakers. Maybe something from Art Audio.