My rear speakers have always been much quieter than the fronts. They are run from the standard oem rear amp. I always assumed that it was just the little amp doing the best it could with the low voltage input it was getting from my upgaded HU rear RCA out. Today, I spliced a high 2 low converter into the HU rear speaker wires and converted them into a low voltage signal which I fed into the standard Audi wiring for the amp and BOOM! Much more volume and power. The volume was equalised from front to rear. Prior to this I had to fade to the rears by about 30-40% before I could hear them at all! So it seems that HU output converted down is more than the 2v the rear RCA puts out? If the HU is putting out 4x50w max, what voltage is it reduced to with a high 2 low converter? i still have the factory speakers but will probably now upgrade them. If I do, would I be better retaining the Audi amp to use with the new speakers, or run new speaker cable to the rear and drive them direct from the HU? Stu.