what’s the difference between the etymotic er20 on the same nine site but with different prices?! Google throws up a few links to the same site for them but two different prices.
It might be that there’s two versions, the ER20 and the ER20XS, the latter have some different features. I use Rooth ones, which I got through Drop/Massdrop, and which I’ve been using for a few years. They work well enough for me, blocking the damaging higher frequencies, but letting me hear what’s going on. They’re much better than the cheap foam ones, which are just to attenuate all frequencies. I’d go for the Etymotics, they’ve been in the business for yonks, and it’s worth spending extra for the quality, and the fact they’ll last for years.
There’s a trick to getting them to fit properly though – lick or moisten the eartip, then pull the outer edge of your ear back and out with one hand, while inserting the eartip into the ear canal with the other. It’s how I fit my IEM/Canalphones, which all have similar triple-flange eartips. Takes a bit of practice, but once you’ve got the knack it’s quick and easy, and you really do notice the difference in how loud sounds are attenuated.