Will a Adcom GFA-555 amp be enough power to push a set of SDA SRS 2.3 speakers?

Only the pin carries the signal, the blade is not used on common ground amps. In fact many have made cables just using the pin of an RCA connector with the outside lips ground off. YES there should be continuity between the blades why there is not I cannot explain. The blade only comes into play when using non-common ground amps or mono-blocs with a dreadnaught or Polk AI-1 cable to create a common ground. Blade/blade cables DO use both large and small blades to send signal back and forth on the cable.

no should not as receivers are common ground 99.99% of the time