You're welcome! Yeah, a pair of Concert Grands is quite an auditory experience! I use to 'clone' their tweeter 'horn' concept using recycled radio/TV drivers to make large 'el cheapo' ~100 Hz 'multicells'.

Its faceplate says Sony TA3200F (early '70s), but according to a service tech it isn't one under the cover, so we assume it's a Japan spec version that he didn't have data on. All I know for sure is that it's a very low -fb/distortion/noise floor, ultra wide BW 120W/8 ohm class A-B SS amp that I prefer over any other amp I've used.

GM