The FPB 600 is DC-coupled and complementary push-pull, with a jumper to allow inclusion of an input rolloff at low frequencies, for use where a signal source ( eg, an incompatible tube preamp), might provide DC or excessive LF. This would otherwise trip the protection, of which the final element is the circuit breaker on the rear panel. Krell FPB 600 amp is in excellent condition. It was serviced last year by Krell (it cost around $1800). See attached for the invoice. There are some scratches on top of the cover. Two-channel, solid-state power amplifier with Sustained Plateau Biasing output stages. Power output: 600Wpc into 8 ohms (27.8dBW), 1200W into 4 ohms (27.8dBW). Krell Full Power Balanced 600 power amplifier Page 5. Aside from the choice of cables (not easy, in view of the performance potential), two further areas remain of interest: physical support and mains power supply. Like the FPB 300, the '600 benefits from something more than carpet under it. In any case, if the carpet is too deep, air flow will The Fpb 600 is an awsome amp, the cx has more sparkle on the top and the cx has an uncanny realisim to the mid-range, and more clear than the original fpb amps, neither less, both models are very fine amps that will give you what you seek for the thiels that need the power to drive them to their top performance that they can possibly do.cheers. Copy of "Owner's Reference Manual for Krell Full Power Balanced (FPB) Power Amplifiers: 600, 300, 200 Stereo; 650M, 350M, 250M Monaural". Total of 15 pages.Buyer to pay for flat shipping cost of $4.00. Paypal fee is included in the price. Reasonable offers will be considered and are welcome.Please