Class D Technology

Yes, top manufacturers still use linear power supplies, but main reason is demand from people who, mistakenly, believe that if it has to be heavy to be good.

Sez who???

Cheers George

Well, most of people on this forum (including you) think that SMPS is noisy and linear power supply is better.  This believe comes from bad rap of noisy crude computer SMPS applications.  They don't even realize that "Linear" power supply is a primitive unregulated switcher.  I addition, many believe that when something is smaller and more efficient something else has to give (that's human nature).  They apply this believe to both SMPS and class D amplifiers (that are basically controlled SMPS).  In view of that amplifier manufacturers would be stupid not to keep using "Linear" power supplies.  Only few true pioneers like Jeff Rowland had courage to develop state of the art SMPS supplies that are extremely quiet  (noise very easy to filter out at 1MHz operation).  Even 50kHz SMPS executed well are far better than "Linear" supplies IMHO.

So much noise about nothing of real consequence.

I will of course look forward to improvements in switching frequency under the assumption that things will get even better overall down the road at least on paper. How much difference it makes practically is TBD.

George I do think you are too obsessed with this one technical issue. You should do a study to see if class d amp sound quality correlates strongly to switching frequency alone. To hell with all the rest that goes into these things if that is all the story. 

You should do a study to see if class d amp sound quality correlates strongly to switching frequency alone.

I have, done numerous bench/listening tests, and tried to come up with my own cascaded output filters like Belcanto I believe did with their 600ref monos, but doing filters this way has a other set of problems (interactive ringing) if your familiar trying cascaded filters for speaker xovers.
Mark Levinson with their no53 also tried it but that fell a bit foul with a Stereophile review/measurements.

Cheers George

 New class AB amp from Benchmark ABH2 also utilizes SMPS resulting in 132dB dynamic range.  

They had to cut costs somewhere to hit that $2995 price point. The dynamic range and THD numbers, while appearing to be unusually good, may be partly the result of using too much negative feedback. I've never heard this amp, but too much negative feedback and you can end up with a soulless amp.