I just recently bought this amp, and it is amazing, but there seems to be a problem with the effects loop. I was trying out my chorus pedal (Ibanez Soundtank Bass Chorus), the input plugged into the send, and output plugged into the return. And the pedal powered by a wall wart. Once I turned the Pedal on, I got a horrible, and extremely loud constant tone, but it was fluxuating because the chorus was effecting the constant tone. With the master and the gain at 0, the tone was very loud. I messed with the effects blend knob on the back of the amp, but that just changes the volume of the loud tone. Is there something wrong with the amp? with the pedal (it works fine just going from the bass -> pedal -> amp)? Thanks.