this review is for both, the 300.2 and 1200.1.
the 300.2 is a 75watt x 2 amp, at 4 ohms. its a very nice looking amp, and thats part of the reason i bought it. for a 2 channel amp, its pretty big, but its really the heatsink design of the amp thats huge, go figure, i've never had an overheat problem with these amps.
the 1200.1 is a class d monoblock, rated at 1200watts x 1 @ 1 ohm. diamond amps are definately underrated. my old 600.1 did around 850watts, and 1200.1 does over 1400watts.
both amps are pricey, but there is a reason.
both feature 5volt inputs, not that bad, but there is better. the built in crossover is great, fully independant and adjustable lowpass, highpass, and subsonic, with a 12db/octave stereo slope, using butterworth alignment, thats on the 300.2, the 1200.1 has the same, but no highpass. the other cool thing about these amps is the power supply, the amp will produce its rated power from 11 to 14.5 volts.
you can get amps cheaper than these, but the crossovers do make them appealing.