My line reference SRPP ( Series Regulated Push Pull ) fitted with NOS Philips ECC186SQ as voltage amplifier and 5687 for low impedance high current output buffer. Power supply is a fine all tube Shunt Regulator. ECC186SQ is the best ECC82 family tube ever made. The crucial mid range ( male/female voices ) is astouning but unfortunately …this tube now It’s very expensive !! All capacitors are MKP or Paper in oil, carbon composite resistors in the signal path, double C-Core power transformer and choke PSU.