So I am having a little trouble with amp noise and just wanted to know if anyone could help diagnose the problem. The amp is a Dr Z Maz 18 NR head. I have RCA 1958 Blackplates in V1 and V2 and a RCA 1960s Greyplate 12AX7A in V3. Output tubes are JJs and rectifier is Sovtek. So when the amp is on with nothing plugged in to it there is a light "shhhhh" noise when I turn the volume up. This is not bothering me. When I plug in a lead and have a guitar running in to the amp I get a really loud hiss and hum when the amp is cranked. The sound is exemplified more by the volume rather than the master volume. I don't know much about amps, but I assume if the noise was more present when I increase the preamp volume then it is a preamp tube issue and if the noise was increased by the master it would be an output tube issue? any ideas? i can provide more information later when i get back to my amp.