Ive just purchased these headphones having used the 310's for about 9 months. Why did I buy them? I wanted headphones with better base response. I can say from experience of the 310's that these are definately better both for base and thoughout the frequency spectrum. They sound sharper and more punchy thanks to the dual drivers that definately gives a better overall sound than the 310's. I also listen to music on Sennheiser HD 595 open head phone, also a class product and the 420's are as good as these if not better.