Speaker noise - hissing

The noise is new...same amp and same speakers. I can hear the hiss from 3-4 ft but, not really from my listening position of 9-10 ft.

I'd bet it is the 6sn7's if it annoys you get some recommendations for some good low noise tubes. The new production EH's are quiet but I don't know if you would like them in your amp. I use them in some Cary amps and compared to some NOS RCA's I have they have a tad more edge, whereas the RCA's are a tad soft/mellow - depends how you look at it, and probably how they blend with your amp and the power tubes.

One other question & suggestion. Is the noise equal between channels?

While small signal tubes are often the source of hissing (aka white noise) and can increase as tubes age, it is unlikely that all four of the 6SN7 tubes are deteriorating at exactly the same pace.

If you find the noise is louder in one channel than the other, try switching the tubes between the left and right channels. If the noise is now louder in the opposite channel you'll have confirmed that it is time to replace those tubes.

Adam, I had the same problem with one of my AA Transtracs last summer. It ended up being one of the output tubes causing the hiss. Luckily I had some extra tubes to troubleshoot and replace the faulty tube.

Adam, one other thing. The AA amps should be dead quiet. No hiss, no noise just a very slight audible hum with the volume full when your ear is about an inch away from the midwoof.