to keep is simple... the power section of the amp ends up acting a lot like a tube amp in it's compression. It does only do about 250 watts RMS, but because of the way the amp compresses the signal, it's overall output ends up being equivalent over time to a higher powered amp. The initial transient will not peak as high as a higher powered amp, but the way it handles the output, it outputs louder and longer than a standard amplifier. It will be louder than any 250 watt RMS amplifier. Possibly you could recreate it with another amp if you had a great compressor in front of it. The TC thing isn't just compression , but from what I've read, that sounds like what it does more or less. I like my RH450. Sounds good through my old 115 black widow cab or my TC RS cabs. Very different sounding speakers, for sure. To me the RH heads have a rounder tubey type sound compared to the BH heads and combos.
They are great amps.