From what I've read and been told (and soon to test myself), the Harman Kardon DVD25 and DVD30 (DVD-Audio) are supposed to be extremely close to the new Arcam CD player that costs about £400 (I forgot its reference).
If you shop around you can get the DVD2550 - same as DVD25 but with bottom half in silver finish - for £250 (rrp £350).
The rrp for the DVD30 is £450.
I do not know how much of a difference they would make compared to the Sony via the Denon though.
P.S: chipster is selling a DVD25 in the classified forum.