Here's the scoop. I bought 5 pairs of headphones trying to find the right thing and I can say with absolute certainty that if you care about sound quality at all, these things are absolutely incredible. They're also inexpensive and super comfy. I love music but I'm not a professional. I didn't even entertain buying something that cost over $100The only other pair of earbuds that have equal sound are the Klipsch S4i Premiums (http://amzn.to/11tkvlK) -- the Klipsch actually delivers a slightly louder, crispier sound, and if I were working in a music studio, they would probably be my choice, but for everyday listening, where I like a warm sound with clear, round bass and a little less crispiness on the highs, the Ultimate Ears are the winners (I found I could listen louder without it hurting my ears with ear-splitting highs from cymbals and snare drums). I even compared these to numerous over-the-ear headphones and found that the sound stage, clarity and comfort was far superior. Why have a giant block of plastic over your head when you can just wear these tiny earbuds and get blown away and completely immersed in sound. Even the ear fittings they provide are amazing. I used the silicone ones for a while (which definitely look cooler), then switched to the memory foam buds (they're like earplug material) and found that for all-day listening, the foam is a little more comfortable.Regarding sound quality: Until you do a side-by-side comparison, I promise you there's no way you could expect the kind of difference these deliver. The best I can explain it is like watching a 13" tube TV versus a 40" flatscreen. It's just impossible to imagine how you ever listened through crappy, muddled, blow-outy headphones before. And for $50-$70, it's worth it (especially if you listen to music all day at work like I do).Regarding noise isolation: I actually was shopping for active noise canceling headphones because I tried a friend's Audio Technicas (http://amzn.to/12lZAbP). So I bought a bunch of noise cancelers too... but in my opinion, it just wasn't worth listening to a high-pitched hiss all day. These UE earbuds block out nearly as much (definitely as much when listening to music) and are dead silent when there's nothing playing (unlike the active noise canceling.)Here are the other earphones I tried:- AUDIO TECHNICA ATH-ANC27 -- http://amzn.to/116QR5Q -- good sound, but clear hiss when active noise canceling is on, and they were terribly uncomfortable (my ears didn't fit inside the cups and they squeeze like crazy)- Audio Technica ATH-ANC23 QuietPoint Active Noise-Cancelling In-Ear Headphones -- http://amzn.to/19t9BUT -- terrible bass response, the sound got blown out almost immediately.- Klipsch S4i Premiums -- http://amzn.to/11tkvlK -- These are amazing. It was really hard for me to choose between these and the UE500s... in the end, it came down to personal preference because I like the warmer sound of the UE500s- NXG Technology Hush Ambient Noise-Canceling Earbuds (NX-HTNC) -- http://amzn.to/13q9h4q -- nope. The sound is nothing like people are describing. It's fine if you haven't tried good headphones, but don't waste your money.Here's the icing. The first pair of these I bought had some weird thing going on where I was getting a tiny static shock every once in a while -- they did not have the microphone on the cable. I called Logitech directly and they sent me a brand new pair of upgraded ones with the mic. I won't say they were the easiest to deal with because I had to jump through some hoops, but in the end it worked out. I later figured out the static was from my office chair rolling on the carpet and it was just grounding out through my earbuds... but the new ones don't have that problem at all. It was well worth having to deal with Logitech, because these headphones blow my mind every day.Buy these or the Klipsch. That is all.