OK techy response for you guys.............
There definitely is a difference between Class D and other types of amps. A distinct technical difference, class D is [b]Digital [/b]and A A/B are analogue. But what does that actually mean?
Class D amps were developed out of Switch Mode Power Supplies and in fact a class D Amp (as in a rig amp) contains a Switch Mode Power Supply (SMPS) and a Class D (Switch Mode) amplifier - both are digital.
A class or A/B works by continuously increasing the 'amplitude' of the whole signal coming in from your bass. It takes what comes in, subject to tone filtration, and makes it bigger. Continuous signal in continuous signal out.
A Class D chops up the signal in into thousands of slices of equal size each with an amplitude ( a value in volts) and then the power amp reproduces each slice with a bigger amplitude (more volts/current). SO what I am saying is the amplification relates to the slices NOT a continuous signal .
Think of it like a modern TV which scans in a new image at 100Hz or 100 times a second. Looks pretty live to most people. Your eyes can't resolve the flicker because its too fast so you see an averaged out smooth image.
Now what is happening in a rig is that the digital signal goes through a low pass filter then to your speaker driver which just like your eye can't resolve at the sample frequency of the digital amp. The filter and speaker do the same job as your eyes with a TV, It produces a uniform tone (moving sound picture) which you hear. You are hearing averaged out slices of your original tone.
That isn't to say it sounds bad to our ears . A modern Class D will sound a little different but most of us won't hear it.
Class D is a compromise between lightness and efficiency and tone.This is the same as between Class A, Class A/B ad Class B. Class A is incredibly pure, low distortion and low noise but at 30W you could fry eggs on it and need massive power supplies, Class B is noisier but more efficient, class A/B a hybrid.
The smart cookies have put valve pre amps in before the Class D so you get tone Plus light power , Genz, Aggi
Its all a compromise - its always a compromise BUT digital is getting pretty good and its set to get better. Soon there won't be an argument to have - unless you have hearing like a bat of course.