Those '70s transistor units. I had a Phase Linear 400 in the early '70s. I count myself lucky a burgular came and took it away along with a pair of EPI 400s. Moved out and bought a pair of LS3/5as and a DH200 kit with the insurance money, so I made out.I still own mine. I couldn’t let it go. However, compared to my Benchmark it sounds so bad (shrill) that it’s shocking.