Another option is trying to find (patiently) another SA-50 and using them as bridged/balanced monoblocks for a differential 200W each. That's what I did with SA-100's, along with XLR cables. Seems like more than the advertised 6dB gain increase.
Those speakers are 8 ohm nominal with 5 ohm minimum and wouldn't be tough for bridged amps.
Those speakers are 8 ohm nominal with 5 ohm minimum and wouldn't be tough for bridged amps.