Concede her point about the hobby angle, don't argue it. Admit that it's a luxury, and let her know it's one you really want to have and that makes you happy. Don't get hung up on betting whether or not she'll be able to hear the difference between the CDP's - even if she can (and she probably can), she won't care enough not to resent being made the unwilling beneficiary of your upgrading. This is for you; be straightfoward about it and ask sweetly (telling her exactly what it's going to cost), and you'll probably be on your way with her blessing - at least to finishing up with your plans for *this* system. (When full-blown audiophilia nervousa hits, OTOH, you're strictly on your own buddy boy... :-)