The only advantages of class-D are high efficiency and low cost per Watt.
Class-D or switching amplifiers are not new and this topology wasn’t designed for hi-fi applications. What class-D does extremely well is deliver very high efficiency and power output with relatively low parts count and cost. The tradeoffs are higher distortion and unwanted RF byproducts that must be filtered.
Don’t let anyone try to convince you that class-D is superior to class-A or class-AB for audio. It isn’t, in any way, except for its low cost and high efficiency. This makes class-D amplifiers great for subwoofer amplifiers and home cinema amplifiers where a high power/volume ratio is important. A good example is where manufacturers need to fit 11 channels of amplification in a chassis.
Manufacturers like NuForce and B&O have produced class-D amplifiers for the hi-fi market, with some success, but at the real high-end, nothing is class-D. There are no advantages to using class-D for audio, where cost is no object. Where cost is a limiting factor, class-D can be used to create high-value products.
“But Mike, lots of hi-fi gear is class-D now and I’ve read that it’s just fantastic.”
I know, I’ve heard it all before. There are no technical reasons why class-D can or will sound better, though it will sound different, for sure. Class-D is used to reduce costs and allow small, very powerful amplifiers to be created. These certainly have merit, but are not technically superior.