I know the prices for these are quite different, I was just wondering if I can expect a significant increase in sound quality with the m100's over the m50's
No in overall sound quality the m50 is better than the m100, If you want something better than the m50 look into mid fi headphones. The m100 are beautiful though not £20 beautiful. The m80 is more in between the two so that may be a better option but i would still give the nod to the ath m50.
Cool, anyone else have any opinions of the m100 in relation to the m50?
What's are your requirements/likes/criteria for the upgrade? I haven't listened to an m50 in ages, so I'm not gonna be very detailed about it, but the M100 has a slightly darker yet more 'fun' sound signature with a bass emphasis and a dip in the high mids; the m50's on the other hand are more neutral and flat-ish. I would say that the M100's are more of a side-grade than a straight upgrade in terms of overall sound quality, but if you're looking for a portable, then they're probably the best I've come across in the price range -- though, I'm not entirely sure if the additional $100 over the UE 6000 is entirely justified in that category.
Depends what you want from your headphone and what you'll be listening to but for me the M-100 slays the ATH M-50 which has to be the single most overhyped headphone i've come across (although that doesn't affect the quality of the headphone itself)