I have been getting a reverb feedback on my LSS 1x12 combo...seems like whenever I turn the amp up past 7 or so, it starts to feed back...The warranty tech said the tubes are fine, but Im having problems using the amp...I keep the reverb at about half strength, and I dont use an effects loop, although I keep the effects active as to utilize the solo feature...someone suggested that I should keep the "send" knob the same level as the "output" on the front panel...The tech is stumped as I am, and he is going to contact Mesa...can anyone help, as I like the amp, but I cant use it...Thanks in advance for any suggestions