Class D vs Class A Education

Polar opposites. Class A is the most inefficient type of operation, drawing about 4 watts for every one watt of input; during this whether they are playing music or not. So they will run cooler at full output than at idle. Class A amps tend to be large, expensive ' and generate immense amounts of heat. Despite this [or because of this if you follow the Audio as Masochist theory] they are regard as the best type of amp by many experienced audiophiles. Class D, on the other hand, can be light, cool running and cheap, they do not draw much current at idle and their design allows them to draw only what is nessary when playing music. Their drawback is that most do not sound that good, so far the ones that sound good are as expensive as other high end amps despite theoretically being easier to build. In a nutshell you could say that the difference has to do with they way they treat current, the D amps can switch very rapidly, the A amps don't switch at all. You can get far more power out of a D amp of a given size than an A amp. All this is vastly oversimplified, I will leave the technical details to others. There is a great deal of lit on both of them.

This statement is a little general, but applies to many - not all. Disclaimer is that I am a dealer, and ahve sold both class A, AB and D designs over the years, but I no longer sell any class D amplifiers.

To my ears, class A or a strongly A biased class AB amplifier exhibits a more emotional involving sound.

In my reference room I have changed amplifiers from a class D design to an AB with a strong A bias, and WITH ALL OTHER COMPONENTS REMAINING THE SAME, the speakers were much more musical sounding, bass was deeper and more pronounced and the system was generally more enjoyable to listen to.

The class AB amplifer was slightly higher in price, $6000 for the class D monoblocks, versus $8000 at the time for the class AB amplifier, but both are very highly reviewed and well liked brands.

I just sold my Spectron Musician III Mk 2 amp (Class D) and bought a used Pass XA30.5 (Class A).

These two are the best I've had in my system, and I've had a few high-end amps before these (Krell, Karan and Burmester).

If you're leaning towards a Class D amp because of the power and efficiency, I'd readily recommend trying the Spectron.

Chuck