Arcam Delta 60, with attenuation set at the recommended -6db (apparently to avoid overloading the tape monitor circuit). The sound was really disappointing…dull, sluggish, compressed. I was stunned. I took everything apart, went back to enjoying the Hanson Zylberberg Monitors.
Two weeks later, I had some time to experiment. I put the Macs back, brought in my wonderful Sansui AU-8500, and because the amp has removable pre out/main in jumpers, put the equalizer between the preamp and power amp, with no attenuation (also as recommended). Now I heard music! These are very nice speakers, full range, with pretty good detail. The softly glowing equalizer on top of the big Sansui, and the late sixties modern vibe of the speakers make the Seventies Stereo listening room feel like Don Draper's place.