Class D Technology

Great thread. I'll add that Class D amps are extremely sensitive to power source and power supply. To hear the best the technology can offer, you would have to pair it carefully with a matching quality power cord and possibly a power conditioner. This took my NCores to a whole new level (refinement, bass, micro detail, etc) and brought out the musicality that had been lacking. 

Ok George we get it.  You aren't sold on class d yet.  Others are. Mine sound great and no faults I could point to when listening.  They just make sweet music as said. 

I am going to chime in here in favor of current class D amps, with a big thumbs up! I have been in the tube amp camp (both SET and others) for 20+ years, and now I am happy as can be with my Red Dragon S500 amp. No, it's not like a tube amp, but it's not SS sounding either.  It does so many things right, and hardly anything wrong, that I can easily live with it. All topologies have their pros and cons.  Throw a tubed preamp in front of a Class D, and there you go! 

George , I did put my ear to the tweeter and I can hear almost complete silence - much better than class AB amp I had before.  I'm not surprised since tweeter membrane has no chance to move at 500kHz.

Modern SMPS are much quieter than linear power supplies that, in reality, are very primitive noisy switchers operating at 120Hz.  Modern SMPS switches at zero voltage/zero current while much ripple is much easier to filter out than 120Hz, that requires huge amount of capacitors (that produce unwanted inductance that is in series with the speakers).  In spite of all capacitors linear power supply in power amps is unregulated.  Because of that Jeff Rowland does not use linear power supplies at all.  He uses SMPS even in preamps to lower noise floor.  Benchmark replaced linear power supply in their latest DAC with SMPS lowering noise floor by 10dB.

Mapman is right - you're not sold on class d yet.  I enjoy my class D amp immensely.  Efficiency is not that important to me (but it should), but is always welcomed as added benefit.