I received a schematic for the Definitive Technology PF-15 (not TL) amplifier. The tech support person imformed me that the speaker driver that works with it was 75 ohms. I have not heard of one with this impedance. The schematic says max of 725 watts into 36 ohms. I have also not been able to locate a speaker this size. The amplifier which I obtained on ebay was stated to be for the PF15 or 1500. The schematic says that it is for BP3000 and BP 2000. This amplifier is in two parts. LL AFAD and HL AFAC.