Dogstar wrote:Now I'm concerned...despite installing new tubes and a Weber rectifier and not having any hiss tonight I turned on the amp and without a source playing hiss was clearly audible. Once the amp warms up the hiss goes away. I do have a volume control on the amp so tomorrow I will run a source directly to the amp and bypass my preamp. If there s no hiss then it may be time to replace the tubes in the preamp too. It takes 4 12AU7's so that would be a good place for the RCA's. If the preamp isn't the source of the hiss then what should I check next?
disconnect the RCA cables to the amp and then SHORT the inputs of the amp, use whatever means you have to short the ground, ie outside of both the amps RCA sockets with the inside, turn the amp back on and see if you can hear the hiss. If no, the problem is external, if yes, its still the amp. This is a really quick way to determine where that noise source is.
Also, can you take a nice, well lit & sharp photo of the inside of your amp and post it here, this will give us a chance to see if there is anything obvious in the wiring etc..