The XPS2 is an improved XPS - larger traffo etc. & I believe it started when the box style changed from olive to the current black case, so that is the easy ID'er.
The XPS & then the XPS2 ran up to the DR change (last year) with LM317 regulators. I believe the XPS cannot be DR'd, or at least Naim are not offering that, might be wrong, but I know the XPS2 can be factory changed. The current XPS2 is DR
A problem with a lot of forum chat is peeps sometimes write XPS & leave out the 2 so don't take it all literally.
The XPS & then the XPS2 ran up to the DR change (last year) with LM317 regulators. I believe the XPS cannot be DR'd, or at least Naim are not offering that, might be wrong, but I know the XPS2 can be factory changed. The current XPS2 is DR
A problem with a lot of forum chat is peeps sometimes write XPS & leave out the 2 so don't take it all literally.