OK - I finally picked up that virtaully mint pair of XPL200A's with DX-1 that PARA had and got them set up, though not with the DX-1 yet, (I still need to drag a couple amps over and rewire stuff). But I did put them next to my 4315A's for some A-B comparisons. For amp/pre-amp I only used a top of the line JVC, (I know - groan...), but at least it runs the 4-ohm 4315A's without blowing fuzes, rated 130 watts/channel.
Immediately, there's a big difference in efficiency, maybe because the 4315A's are rated 4 ohms and the XPL200A's are rated 8 ohms - switching back and forth, the 4315A's are much louder, at least for a given volume control setting.
Next, (and this surprised me), even set flat, (but adjusting for ~ equal volume), the XPL's had much less presence/midrange than I was expecting. And I expected to hear a significant difference in clarity, etc., but the 4315A's really surprised me - at least to my ears, they seemed quite as clear as the XPL's. I've always been happy with the 4315's, but I still expected more difference.
I guess the next thing I need to do is to run some RTA curves to see which speaker tonality is actually flatter between the two. Much comparison is needed in the future, including setting up the DX-1 and running everything off dedicated power amps. I'll keep revisiting this thread to post new observations, but it will be over a matter of weeks...
Anyway, here's a pic of them guickly set up. I'm tracking down some kind of rack so I don't have such a mess, but again, it might take a little while.