So I picked up a pair of CX300s today at a local Dutch mail order shop for 39.90 euros. Even though I do not post a lot here, I have been around for some time and (have) own(ed) an EX71, E2c and now the CX300. I bought to as a pair I can throw around without caring about the price tag.
Enough bull, you're not here to read about that. I won't go into detail about the packaging and everything, but I should note that they look really nice and are a lot less extravagant than my Shures. Good point and an advantage for the CX300s.
Isolation is ok, but neither spectacular, nor disappointing. The style of the earbuds just cannot offer isolation up to par of the Shures or Ety's, or any equivalent true canal phone, but it does its job. As has been noted before, microphonics can be a real issue with the cable, but I have never been bothered by it before. Actually, they are very similar in terms of isolation, comfort and microphonics to the EX71s. The cable looks weak and bound to break, but you get a warranty, so you should be fine. However, judging from how the EX71s deal with minimum abuse, I cannot recommend careless use if you plan to cherish these earbuds for your life..
So how do they sound? Bassy, yes.. However, I would not call them undefined in the bass department, so nothing compared to the EX series Sony offers. They have a tad more bass than the E2s, but for me it's not disturbing. The mids are ok and definitely better than the EX71s, as are the highs. The overal sound these earbuds produce is just phenomenal for their price tag! However, I have seen people claim that they are the best earbuds under $100, but I wouldn't jump to that conclusion too quickly. The E2s, eventhough considered to be veiled off, have clearer and more detailed mids and also the highs are less sharp and more detailed than the CX300s. Of course, the Shures in europe retail for about twice as much, so they Should be in a different league. The CX300s lack this extra detail up there, but that does not make them bad earphones. I am very impressed with how they sound, but if you own both you will know what I'm talking about. It's this extra crisp and detail I miss, but it's up to you whether you even hear the difference or are willing to pay for it.
One plus for the CX300s though is that they are very very (very!) easy to drive. I cannot see the point of amping these, so you should be fine. Amping the E2s adds a little extra, not much, but I doubt whether the CX300s even benefit from an amp, unless you have a really lousy mp3-player.
Soundstage is ok for earphones. I'd reckon they seperate a bit better than EX71s, maybe because the bass is more defined, but the E2s offer a better soundstage and overal clarity.
The CX300s then are very nice earbuds for their price tag and will serve exactly what I bought them for; a pair for careless behaviour where superior audio quality is not really needed and less isolation a welcome addition (my E2s totally block me from the outside world and sometimes there are situations you'd prefer to know at least a little of what's happening around you). If you have the budget to spend, imo, go for the Shures or the Ety's, as these are NOT the best earbuds you will buy under $100 in terms of audio quality. These earbuds might however well be the best price/quality offer and if you're looking for an introduction to the world of canal phones, truly consider them. If you're looking for a replacement for anything from E2s, E6is or up, don't bother and look further, because these ARE a notch down in sound quality.
Everybody who got them: enjoy them!
ps.: they seem less suited for rock music (probably missing the clarity on the mids and highs here), but acoustics sound really rich and full.
