hmmm,

i don;t thing sampling an analogue signal at a high sample rate IS the same thing as upsampling. sure if you are using a cd as your source then you are going to have a lot of wasted bandwidth above 22.1khz but with vinyl or dvd-a etc. then a sample rate of 400+ khz is going to be fine. i can't see the need for any kind of upsampling in the amp as upsampling (or sample rate conversion) is only necessary when you are trying to make something fit that wasn;t intended (i.e. changing a sample rate of 44.1khz so that it can be decoded by a 92khz dac). similarly if your digital amp works by manipulating a bitstream rather than words it would be sampled as a bitstream again negating the need for conversion of any sort.

cheers

julian