My amp goes quiet randomly and stops playing even though its on. I've read up that the tubes they put are cheap and its probably the powertube that went. But I just bought this guy.

If i call the company there going to just send me the same amp with the cheap tubes and i will have to keep going back and forth.
Never heard that before. But try replacing the tubes. If it doesn't help,put the old ones back and send in for a different one. If THAT doesn't work- new amp.
well i dont want to void the warranty so i dont want to change anything.
changing tubes wont void the warranty.
in fact, normally your amp will have a warranty of anywhere from 1-5 years, and the tubes will have a 6 month warranty. take it back to whoever you bought it from, and they will look at it for free. because of the warranty.