Class-D or switching amps, any opinions on??

Here is a pretty good Wikipedia article on noise shaping. Very basically, oversampling + noise shaping allows the quantization noise resulting from the limited resolution to be mostly shifted up to frequencies that are higher than the audio information, allowing it to be digitally filtered without significantly affecting the audio.

Regards,
-- Al

Al - Thank you for the link. My problem is with resolution. As you said TACT stated resolution from PWM is 8 bit. Where do they get required extra resolution (possibly by adjusting power supply?). 384kHz carrier sounds about right (Icepower is 400-500kHz).

Class D is here to stay. Some people don't like the concept of switching in audio but delta-sigma converters, SACD and DDS recordings are exactly that (PWM).

My problem is with resolution. As you said TACT stated resolution from PWM is 8 bit. Where do they get required extra resolution?

Kijanki, though it may seem counter-intuitive, reducing the quantization noise that results from limited resolution is mathematically the SAME as increasing the resolution, apart from any possible side-effects of the digital filtering processes. So they get the required extra resolution by the oversampling + noise shaping + dither processes that I referred to.

Keep in mind that limitation of resolution to a finite number of bits is mathematically identical to summing a noise component ("quantization noise") into the signal. If I recall correctly, assuming random error distribution (which is pretty much assured by applying proper dither), the rms quantization noise amplitude is equal to the lsb increment (in volts) divided by the square root of 12.

The oversampling allows most of the quantization noise to be shifted to higher frequencies than the audio information, where it can be filtered out with minimal impact on the audio. Dither randomizes the process to eliminate "deterministic errors," as the article indicates.

I believe that the other pwm applications you mentioned, delta-sigma converters, sacd, and dds, do the same thing.

Regards,
-- Al

Al - they do, but carrier frequency is almost 10x higher and resolution is 16-bit. SACD pulse width modulates at 2.8MHz - said to be equivalent to 20-bit on non-oversampling system. My analog class D amp (Icepower 200ASC) runs at about 500kHz with unlimited resolution. There is no quantization noise since it is not a sampled system.

I have been enjoying the Red Dragon Leviathan mono blocks.
They replaced Classe DR 8 monos, and Cary 300sei.

I have used them with Tanoy Arden,Merlin TSM MMX, and Ref 3A Grand Veena.

I have experienced all of the pros and none of the cons when people describe D amps.

Very satisfied and trouble free.
First amp I have ever left on 24/7.