That is a blast from the past! I use to have Acoustat in the mid 60s; at least one pre and an amp I built from a kit. They carried the Xs at Allied Radio, which I use to frequent. They had a built in amp if I remember. Should still be a good speaker but anticipate some expense in bringing them up to running condition unless you are very lucky. Remember that a powered full range electrostat costs north of $10,000 these days; often way north. Worth putting some money into if you can find someone who can do the work.