I was just googling around for information about Tripath (the company that makes the "Class T" 'digital' amplifiers) when I discovered something disquieting:

http://en.wikipedia.org/wiki/Class_T_amplifier

Despite superlative performance at low cost from the Class T approach, financial difficulties have caused Tripath to file for Chapter 11 bankruptcy protection on 8 February 2007.

Tripath used to sell the amplifiers as chips, or as chipsets, to be integrated into products by other companies in several countries.
The term "used to" seems to indicate they're no longer selling these and their website address is no longer valid:

http://www.tripath.com/

and Google can't find any alternatives.

Are they really gone? That would be a shame. A company making excellent, well-loved products in financial trouble. Reminds me of IMAX. :-(