It's going to boil down to a lot of factors. I have owned a few class D amps, in fact currently own a pair of Ref 1000 by BC. In comparing the class D amps over the years, in evey comparison I have made to my class A amps (which have traditionally been Krell (4), Pass (2) or M. Levinson (3), but others as well), I have preferred the class A amps.
Across the board, my preference has been and continues to be class A. But, the class D amps have gotten gradually a bit better with each new generation - but still haven't proven to me to be top performers.
I'd look for a used Bel Canto over the W4S, but that is just me. I know W4S has a lot of proponents. I can't say from experience that you will notice much of a difference. The class D amps always made me feeling as though I was just missing something in the performance and that I couldn't always or immediately put my finger on it. My first experience with class D was pretty positive at first, but over time I came to realize that I wasn't as excited to sit down and listen to music or didn't listen as long.
Across the board, my preference has been and continues to be class A. But, the class D amps have gotten gradually a bit better with each new generation - but still haven't proven to me to be top performers.
I'd look for a used Bel Canto over the W4S, but that is just me. I know W4S has a lot of proponents. I can't say from experience that you will notice much of a difference. The class D amps always made me feeling as though I was just missing something in the performance and that I couldn't always or immediately put my finger on it. My first experience with class D was pretty positive at first, but over time I came to realize that I wasn't as excited to sit down and listen to music or didn't listen as long.