Hi tobz67,
You've been listening to the fat, bloated bass from the old Realistic 10-inch drivers so long that you like it, prefer it, and it's become a kind of sonic reference for you even though it isn't accurate of natural. Lots of older JBL speakers and other brands had that tonal balance, and some people still love it, but it isn't neutral. Many club speakers in discos and the like have a similar unnatural pumped-up bass response for dance purposes.
Once you get used to the smooth, unexaggerated bass from the M60s or M22s (or M80s), you'll find the heavy coloration of some speakers 200-Hz bass hump quite unpleasant.
Regards,
