02-20-12: Eldartford
Kal... I guess I would prefer option A, which, as I understand it simply means using a 300 watt amp for the speaker.
I don't see any advantage to using more than one amp unless there is a line level crossover.
Headroom reduces risk of clipping.
Well, there's still an advantage to bi-amping straight into the speaker's passive crossovers because bass-heavy passages still won't use up all available power and current, leaving little for the mids and tweets. With a separate amp for the woofers, the mids and tweets have a fuller dynamic range unhampered by power and current being siphoned off by the needs of the woofers.
I have had a pair of dual-terminal Mirage M5si's for nearly 16 years, and have ampified them with a wide variety of configurations. I've tried everything but line-level crossovers. Passive bi-amping with high-current amps has the most speed, transparency, frequency extension, and dynamic range, especially compared to single-amping, though bi-wiring helps.
Even if you decide on a single high-powered amp, you should probably still bi-wire and maybe even tri-wire.