I have owned both. The obvious diffeence between the MKI and MKII is the finish. Not so obvious is the increase in woofer size from (if I remember correctly) 12" to 13" and a slight crossover change. The actual construction of the cabinet is also different. If you look at the bottom of the II yoiu will see that the crossover is installed with an access panel. As far as the sound, I don't remember there being much if any difference. I felt that it was a great imaging speaker that really liked to be fed a tube amp. With the right electronics they completely disappeared.
Enjoy
Enjoy