Thanks for the replies gents.
Connection is using the analog outs on the CD player, so we're using the DACs on the player, which are the Wolfson DACs.
I'm not too familiar with the Wolfsons, which is why I'm wondering if this is really the difference. I know the Denon has the Burr-Brown DACs.
Receiver is a JVC RX809V - a bit long in the tooth, I'm 'fraid. I also wondered if this was just a case of mismatched components. But more and more I'm thinking it's just the player.
I agree about speakers (and some headphones) having a "break-in" period. I have experienced this myself, and a number of speaker and headphone manufacturers actually specify break-in periods. Though it does take longer than a few seconds. It's usually at least a good 24 hours worth of continuous play, and sometimes more. Pretty much everybody I've ever talked to who bought Grado headphones has said they sounded like crap until they had gone through proper break-in.
I've heard conflicting reports about electronics items having a burn in period. Something about the electrons finding/etching the path of least resistance through new circuitry and components, and then the rest of the electrons thereafter following the established paths or something. I guess it must be a bit like ants or cockroaches when they find a path to a food source.
Haven't decided if I believe it or not. So I was just wondering if anyone experienced this with the Integra in particular.