I have very recently purchased some of these 'phones. Previously, I had owned various 'budget' models and then the Sennheiser CX300 (version 1) and then the CX300 II model as reviewed by WHF and recommended at £40 - I was well pleased with my purchase off Amazon at under £15. I found them comfortable, more spacious, with better detail and a nice 'warm' sound enriched by what I perceived to be a decent bass.
Then, some rotter of a friend let me try a pair of Shure 420 'phones - mmmmmmm! I was amazed at the leap in all-round quality and realism. However, he told me that he got them as a bargain at £110 last year! Ah, not sure I want to pay that much, even if I can find them at such a price - I don't really do that much 'serious' listening via laptop or iPod.
But it got me interested in the potential of intermediate level earphones of a similar type and, after a bit of checking on the Web, I purchased the ER6i pair off Fleabay at £60. Yes, a bit of a risk, but the reviews and price were good.
I now know why opinion is so divided over these 'phones. When they arrived I was really excited and hurriedly gave them a try on my laptop. Well, I have to say I was rather disappointed. Yes, suddenly the sound opened out and the upper end of the scale acquired a clarity and precision that I wasn't aware was missing from the CX300 IIs, but where was the 'enhanced bass'? I tried various of the ear fittings, but the bass eluded me. I finally got something approaching what I expected when I read the instructions more closely and shoved the flanged earpieces down the ear canals more fully. Not sure I liked the feeling of that!
However, having compared the sound of the Sennheisers on both laptop and iPod over the past few days I have come to realise that I am beginning to prefer the ER6i sound. It should be noted that the difference in sound between laptop and iPod is distinct, and you can tell that the ER6i does arguably sound better on the latter. The CX300 II sound is not warmer, as I first thought; it is bassier and more woolly towards the bottom end. The top end is less crisp and clear. In a way it sounds more intimate and warmer, but maybe a lot less accurate. On the other hand, for under £15 I still think the Sennheiser offering is a steal...and, until I get used to the ER6i fitting, far more comfortable!
As with all things hi-fi, at the end of the day it comes down to personal taste and the source you use. One person listening to the same model of earphones on a laptop will hear something different from another listening on his/her iPod. Because our ears are all made differently, these various earbuds don't necessarily suit everyone. Which makes me wonder why enlightened retailers don't offer a try-before-you-buy service, perhaps at a nominal charge to cover the cost of keeping a stock of extra buds or sanitiser. It would make buying earphones much less of a minefield. Or am I missing something?
Anyway, the ER6i 'phones are getting a qualified 'thumbs up' from me - not as comfortable as I had hoped, but I won't be wearing them for extended periods. If anyone knows of compatible fittings, I would be interested to hear about it.