I have a set of Acoustat 2+2's and obtained beneficial results from replacing the three electrolytics in their input section with North Creek Zen capacitors. The huge Zens barely fit and are now, sadly, discontinued, but you could probably find similar replacements. I've read that the blue and red medallion upgrades -- assuming you can even round up the parts these days -- don't yield noticeable results.
Amplifier-wise, I've run mine on a McIntosh MC7300, an Acoustat TNT-200 (modded), and a Hafler 9505, but what bested them all in my setup was a PS Audio HCA-2. These class D amps are selling used on Audiogon for less than $600 these days.. a steal, and imho, a fine match for Acoustat speakers. Research the HCA-2's SDAT output section and its 'high damping factor load invariant power' to get more insight into why this is so.
