I have cd-5s, and I have listened cd-5 before my purchase. There are quite numerous upgrades between cd-5 and cd-5s model. USB-board is one of them. Also analog inputs (now 1 balanced and 1 unbalanced, before 2 unbalanced) are not digitized (AD-converted) as before. There are also one analog (unbalanced) output for subwoofer etc. Display information is wider and contains more display options (as with cd-1sc for example). There are more switches in back to select different setups (example "normal amp" and "direct amp"). About sonical differences cant say anything yet, because im still under break-in period. But it sounds very good right now !