I'm looking at buying my first set of vintage Polk SDA speakers and have an opportunity to purchase a pair of SDA 1bs. Any comments on their relative sound/value? Also, I had read on another board that in order for the SDA process to have an effect the amplifier you use must have a common ground (I'm guessing this means a 3 pronged power plug?). Is this correct? The amp I'd be using this with is a vintage, completely modified Pioneer Spec 4 Amp which has a two pronged (old style) plug. However, the Pioneer also has a terminal on the back for a ground wire to be attached and I'm (again) assuming I could run a copper wire from that to the metal chassis of the amp or another piece of equipment and that could accomplish the same thing?
Thanks for any ideas/suggestions about these speakers and also appreciate any info on possible incompatibility issues.