I get hum in my system because of TV cable. If your stereo in connected to your TV system in any way via VCR, DVD etc try disconnecting the TV cable at the wall. I have never solved this problem and will probably to to DirectTV to "solve" it. Its the cable companies fault-bad grounding. The hiss might be due to several sources. 1. Bad tubes - Replace with low noise tubes. 2. Impedence mismatch between the amp and pre amp. If the amp has a lower input impedence then the output impedence of the preamp, that's your problem. Solution is a new amp or preamp. Its in the design. 3. Did you test the hiss under normal listening levels? All tube preamps will have some hiss and if you crank up the volume you will hear it.
Hum and Hiss with Tube pre-amp
I recently got a McCormack DNA1 Deluxe and initially used the pre-amp section of my Arcam Alpha 9, and then a Creek OBH 12. No problems, but no excitement!!! I decided to try a tube pre-amp. I have tried a Melos MA 111 and a Cary Ae3 kit that was up-graded in many ways by it builder. Both of these units are reportd to work fine by their owners. When I put them into my system (front end of CAL DX 1 cd and Rotel -entry level- tuner) I get very audible hum (60 cycle) and hiss(like FM hiss). I have tried cheater plugs on both amp and pre-amp to no avail. It was suggested that I disconnect the inputs to the amp and turn it on to check for noise- I did this and there was no noise. This suggests the problem is elsewhere. Since the tube pre-amps worked fine in other systems, they do not seem to be the culprit. But then again, with the ss pre-amps there was no problem, apparently ruling out the front end. But that leaves NOTHING causing the obvious problem!!! Any ideas?? Thanks for any and all help. Rich