Kan 1 can be fun when driven hard, but they are a bit wearing no matter the source material. Kan 1 at low to moderate volume level are a bit shit. Switch over to Kan II, especially so, the later Kustone variant, and it takes a few tracks to realize that the tweeters aren't actually fried. Once one adjusts to this, they are a much better all-rounder.
Obviously, these are my own subjective impressions, however, they are based upon having owned all of the variants, including both early Kan 1 (both Scan-speak and Hiquphon tweeters), Kan II, and Kan II Kustone, some at the same time. I still have the Kan 1 (Hiquphon) which I occasionally pull out and thrash the hell out of for old times' sake; particularly so in the Before Times, I really enjoyed beating the Kans for visitors; the looks on their faces resembling those of kids' first visit to Baskin-Robbins.
The best sound I ever heard from Kan was immediately after
@mykel replaced his Scan-Speak tweeters with the then new cheaply made Ninka (Neodymium) ones. Cassandra Wilson (was it 'New Moon Daughter'
@mykel) suddenly sounded like a woman I'd love to cuddle with in front of an open fire for eternity. With benefit of hindsight (hindhearing?), it wasn't the quality of the tweeter so much as it was the response falling neatly between that of Kan 1 and Kan II.