Subs are usually fed by line level outputs from the receiver, with the amplification being in the sub. If that's the case for yours, I would guess the problem lies with the sub, not the receiver (but I'm not an expert).
Subs are usually fed by line level outputs from the receiver, with the amplification being in the sub. If that's the case for yours, I would guess the problem lies with the sub, not the receiver (but I'm not an expert).