Database reports 12 watts per channel. $500 list price when new. Ebay sales prices range from $42 to $151 with an average around $85
Not sure if the unit takes the plug-in decoders but since I have reports of "higher numbered" units using them it makes sense they do.
SQA-1 Front/Rear logic
SQA-2 Full logic (but, full-logic was a term used as early as 1974 with later decoders calling themselves full-logic that used different "full-logic." In other words, "full logic" is akin to "all natural," it can mean almost anything) $56 to $280 eBay sale prices.
SQA-2B full logic. Receiver has to be designed to accept this plug-in decoder.
Info hard to find on these plug-in decoders. I see them pop up every once-in-awhile at eBay.
Personally, if you're gonna spend the money perhaps a bit more to get a more powerful unit? And, something to consider..... the high end higher priced units when they sold new were apt to be bought by someone that would take better care of it.