PS Audio BHK Signature 250 Stereo Amplifier (price reduced)

Bascom H. King’s magnum opus combines a vacuum tube input with a powerful MOSFET output capable of 250/500 watts per channel.  Around five years old. Purchased new, placed on amp stand, never moved other than to change speaker cables. No marks or scratches, other than a small one on top visible with a flash light. 

The BHK Signature 250 features a balanced differential input stage using a matched pair of 6922/6DJ8 tubes, and a balanced differential power output stage using metal-oxide semiconductor field-effect transistors (MOSFETs).

Most MOSFET-based solid-state output designs use complementary symmetry: n-channel MOSFETs for the positive part of the signal, p-channels for the negative. The BHK 250’s differential-output amp exclusively uses n-channel devices, which, they claim, produce lower distortion and perform better overall. However, using n-channel MOSFETs for both the positive and negative signals requires some design innovations, as Bascon King explains, while admitting that this produces greater amounts of odd-order harmonic distortion than it does the less-innocuous even-order distortion, and necessitates the use of global feedback. Still, he felt that the decision to use only n-channel MOSFETs is one of the reasons the BHK amps came out sounding as they do. The specs claim less than 0.1% total harmonic distortion, 20Hz–20kHz, indicating that this design may indeed trade ultralow distortion for what PSA claims is extraordinary sound.

OEM tubes replaced with NOS RCA 6922 (matched pair).  Maybe 300 hours on these RCA tubes. I can roll them to NOS Tungstram PCC88, Bascom King’s preferred tube (matched pair) on request.  

Ships to USA only. No PayPal fees. Original double box:  22” x 20” x 13”. Shipping weight is 85 lbs.  please calculate shipping using these numbers. FedEx only fully insured.