I wrote several issues back that my first high-end headphones were Koss Pro4AAs, which I bought in 1972 following a positive review in the British magazine Hi-Fi News. Although that review didn't mention that the Pro4AAs were relatively fragile (footnote 1), I nonetheless loved their sound. They were the best headphones I'd heard—until, a couple years later, I was playing bass on some sessions for record producer Tony Cox. Tony had a pair of signal-energized electrostatic headphones, Koss ESP-6es, which were heavy and clunky—but they opened my ears to the sound quality that could be obtained from "cans." I didn't hear better until after I'd moved to Santa Fe, in 1986, and J. Gordon Holt loaned me his review samples of the Stax SR-Lambda Pros.

Last spring, when I was listening to Bowers & Wilkins's 802 D3 Diamond loudspeakers, Classé Audio offered a pair of their new Sigma Mono amps for the review. They claimed a synergy—B&W's D3 series had been developed using Classé amps. I declined, only because using unfamiliar amplifiers would add to my assessment an uncontrolled variable. Now that the B&Ws have settled in—three 802 D3 Diamonds across the front, two 804 D3s at the back—it seemed time to hear what they could do when driven by the Classés.

The Muraudio PX2 ($US79,500/pair) was introduced at TAVES 2016, and sounded very impressive indeed…