i went to the rehearsal room yesterday and plugged the amp. It sounded great on its own until i activated the loop: from hard bypass to loop active. Then the sound became very low and thin (like listening through radio speakers). No extra noise crackling or popping just the problem mentionned above. I activated the loop because i wanted to use my decimator pro rack g. On that unit all settings were minimum (threshold and the other knob i forgot the name of). Then i bypassed the channel on the decimator sio it wasnt active and the problem remained. I then took out the unit and still the same. Could it be coming from the tube in charge of the loop? i am asking that because i dont know wether a faulty tube could do that. Im used with all sorts of problems coming from tube such as noise crackling and popping or just no sound but never that. i also played with the send level but to no avail. any ideas?