David12, My QX4 is plugged into the wall and the PurePower 2000 is plugged into the QX4. The CD player and amplifier are fed by the PurePower (no pre-amp). When needed, the PP has reserve in its battery; so, I have not had current problems with my 600 watt per channel RMS amplifier. In fact, the amplifier sounds better going through the PurePower than directly to the wall.
John
John