I recently got back into playing, and I've been through 3 Hartke practice amps over the past month. The first two were A35s, one had a broken jack, the other an unbearable hiss. So I tried the A70 to see if I could avoid some issues, but it ended up having the same hiss that turns to a buzz if the treble or mid is touched. it happens with nothing plugged in too. is this something worth getting fixed, or should I send it back to sweetwater? I like the tone of the amp but the hiss is driving me nuts. is this a common thing with hartkes? or just something I have to put up with on practice amps?