Upgrade Esoteric K03XD to K01XD?

If you don’t care much about spinning CDs, and your focus is streaming, I would recommend upgrading to the N-01XD. It’s a streaming DAC. No need for a separate streamer. You would then get rid of both K-03XD and N-03t

P.S: the streaming module inside the N-01XD is certified Roon Ready endpoint 

I hope my local dealer here in the UK will be able to get hold of a K01XD to try it out at home. 

That would of course be the best path forward 

I can see the thinking behind the idea of repIacing the current streamer and cd player with the N01XD but I have a fair few cds and I'm not quite ready to abandon the possibility of playing discs altogether

Or you can get a simple CD transport for that purpose, hooked up to the N-01XD via AES/EBU or S/PDIF. 

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.

The clock output in N-01XD is a Word Clock (not reference 10 MHz master clock), and can be set to 44.1 or 48 Khz. So it depends on what the clock input format on CD transport is.

As far the quality of the DAC in the N-01XD vs. K-01XD, it is the same DAC. However, connections, layout, wiring, etc. are different, accommodating just a streaming module in the N-01XD vs. an entire CD drive in the K-01xd. I have read from people in the internet that as a DAC alone, the N-01xd is better, but, don't take my word for it.