I bought a SA5905 today. I'll just say the price was very right and I'll decide later if I should keep it or not. It sounds like this may be a highly sought after unit and when I'm done with it, it will be very sweet, indeed! Right now it's trashed and needs a thorough cleaning. I am going to rebuild the wood casing this summer. It's been battered and the vinyl wood grain cover is delaminating. I will decide whether to redo it in particle board like it is and recover in vinyl wood grain or use a nice whole grain piece of wood. Doing the latter would indeed make this unit a one of a kind. The first thing will be to clean all the electrical components. Then I can put it on the scope to check circuit paths before connecting any peripherals.
If anyone is interested, I just ran across an Ebay listing for a brand new unopened box SA5905! The story is sad. The gal that owns this is getting help from someone to help her sell stuff from her mom's house. Back in the late 70's, her dad wanted some TOTL stuff, went to the stereo shop and the salesperson sold him the 5905 and Cerwin Vega U321's. The dad brought them home, put them in his man cave basement to set up and he passed away! The boxes, unopened were left in the same spot all this time! The helper sold the speakers and has the 5905 on Ebay for what may be the decent price of $2500. With no market data, it's tough to know if this is high or low. One sold in 2020 on the Canuck Audio Mart for $1250US. I'll share this on a couple of the other AK Optonica SA5905 queries as well.