older dacs

I have decided to go with a dac rather than buy a new cd player. I feel the transport on my sony dvp s-7700 is still good.

I do have a question however. Has the technology changed that much in dacs where it warrants buying new. Am I better off to buy something that is a few years old for $500 or buy something new for $500. The one that is $500 used probably cost over $1000 new at one time. Not that price always relates to performance.

Also what are your thoughts on tubed dacs. The rest of my gear is SS and I like to leave it on. Will leaving a tubed dac on just put unnecessary wear on tubes.

Let me know