Hello all. I recently bought a brand new Peavey 6505 head and slant cab. It was working great and exactly what I wanted out of it, however i took it over to a friends house and there was issues. It was very quiet, and had low gain, and my settings were the same. I play with Low at 5-6 Mid 2 Treb 5-6 pre 6.5 and post 3. It's what I've been using since i got the amp and it sounded perfect. Now, its all diminished and quiet. I'm hoping it's nothing technical or tube related as it is brand new. I do have a warranty but I would hate to ship it back since it's so bulky. Anyone have any ideas? I've done a lot already. . . checking the cables, checking the settings, crunch button, guitar volume, pedals on/off, etc. Any feedback on what you think I can try before I unfortunately deal with the company would be greatly appreciated!
If the problem still presents itself when you've taken the amp back to your house, then it's likely a preamp tube.

Does every pre tube light up?
Contact Peavey support first and visit the Peavey Forums as well on their website.
Check to make sure all of your power tubes are firmly seated. I took mine to a gig one time, and when I brought it home, it sounded kind of like you described. It turned out that one of my power tubes had gotten jostled slightly out of its socket and it wasn't operating. I pulled it out and bent the clips a little so they'd grip it tighter, re-inserted it, and it's been great ever since.
Yea that sounds like a loose power tube to me. That same thing happened to me once and I just adjusted all of the power tubes while the amp was off to make sure they were seated firmly. Congrats on the amp by the way- thats awesome