I’m sure Naim (or Class A) are perfectly capable of servicing a Flatcap. Perhaps there are parts shortages or time delays related to Covid, Brexit, broken cargo ships or whatever, but hopefully these are just temporary.
Too many variables to know. I did not get to hear the 2X after service.
That said, the fresh FCXS sounds better with headphones/Headline2– noticeably less “glare”.
I used to use it with a NAC 112 and CD5X, but now I have a NAT05XS, CD5XS, and Headline2; so the FCXS matches better.
AV Options did say there is a small revision in the XS versus the 2X that makes a difference. I do not know if servicing the 2X brings it to that level. All I can say is headphone listening was a bit ragged and drove me to get the service.
I borrowed a used HCDR to try on the Headline and found it better still (darn it!)
My guess is that the difference between the 2x and XS is marginal compared to the uplift of another HC, but I am also learning, that whatever advice you may have, the only way to really find out is to try it in one’s own system.
I have seen differing opinions over the years as to which combinations work best.
For example, most seem to agree that the HC and HCDR are superior to Flatcaps, but opinions do differ as to which, if either, is better on e.g. a CD5X or CD5XS.
Similarly, the SN3, bare vs with HCDR, has enthusiastic fans on both sides.
On the other hand, I think the HCDR is hard not to like on the Headline2, other than that it makes it a rather expensive headphone system.