Ignoring the crazy price, just a neat bit of kit to look at. I'd be interested to know when these came about. The hows and the whys. Seems earlier than the 50 and 100w solid state heads that came out in the back half of the 70's. Thoughts?
https://page.auctions.yahoo.co.jp/jp/auction/n393458540
https://page.auctions.yahoo.co.jp/jp/auction/n393458540
