Thanks for your reply.
I had a look at the Esoteric website but don't know what differences in diagrams would mean regarding sound quality.
I have very few SACDs.
If the DACs are the same in the 01XD devices, and better than in the K03XD, and as I play CDs not that often anymore, it makes sense, as thyname suggested, to buy the N01XD and add a reasonably priced transport. The N01XD is somewhat cheaper than the K01XD and I would be able to trade in my K03XD and the N03T.
The N01XD has a clock output which I could attach to the transport, I assume. I read this would enhance sound quality for CD playing.