I own an S40; is a K22 a good addition to the audio quality? Will I really see a significant improvement, the S40 as a server and the K22 as a player?
Substituting the K22 for an S40 should bring a significant of enough of a sound quality improvement to justify the cost. Once you have the K22, it won’t be difficult at all to determine whether it worth continuing to hang onto the S40.