Very nice Williamson circuit (or close to one). The output tansformer seems identical to that of the Radio Craftsman C-500 amplifier.
I have bought 3 pairs of these with my best friend. but never had a chance to listen to them as he had suddenly passed away. He only finished restoring one pair and claimed the they easily rival his MC-30s.
I already left the US and went back to Israel due to family reasons and the amps and rest of his gear were sold by his widow 😕..
Interelectronics was a small NY based company aimed to compete with Marantz. Rumor has it that later it changed its business direction to become Intel...