Ok so when I plug the amp up and play a few chords its fine.... if I turn the bass up or hit a power chord (G does it everytime) it starts sounding like really low toned feedback starts. It will not stop regardless of me unplugging the guitar from the amp or turning all the volumes down to 0.  This is a Silvertone 1464 SolidState 100. If someone could point me in the right direction Id appreciate it. Thanks!