Class D circuitry allows the amp to be powerful (500w @2Ohm/ 250w @4Ohm) and also surprisingly light at 11 lbs.
But this is just the start: the preamp section lets you select from 11 amp types that are modelled after some of the world's best known bass amps. The 5 band EQ secion lets you choose the center frequency of each band, and there is also one fully parametric band like that in the Yamaha NE1 pedal designed by Nahtan East.
Add to that a fully featured Compressor with all the controls you would expect from a studio unit (and a great sound too), plus Noise Gate, Output limiter, Crossover and Speaker simulator, and you have a feauture loaded unit.
All those controls and options would be useless if you could not store your sounds, but the good news is that that there are 5 user memories. The onboard MIDI connections mean you can hook the amp to your MIDI effects unit and change the effect and the sound of the amp at the flick of a switch (or a pedal).
If you are not sure how a digital amp sounds, don't worry. Yamaha have used 24bit AD-DA connverters and 48Khz sampling, so expect nothing less but pristine quality and full bodied sound.
To sum up: great sound, maximum versatility, programmable and incredibly light.