Quoted from REL setup instructions:
"The standard high level hook up procedure is: attach the red wire to the amplifier’s right positive speaker output terminal; attach the yellow wire to the amplifier’s left positive speaker output terminal; attach the black wire to which ever of the amplifier’s ground output terminals is convenient; plug the Speakon connector into the sub’s high level input.
For differential amplifiers using one sub, simply use the standard connecting scheme with the exception of connecting ground to chassis ground, not to speaker output ground, and then connecting into the high level input (Hi Input or Unbal Hi Input on Stentor III and Studio III). "
The distinction is made above that connecting a single sub to a differential amp. requires a slight modification. I quess my question is...is the 4bsst a "differential" amp?