The TR 55LX sounds decent enough for its price point, but there are other headphones, such as the Audio-Technica ATH-M30 and ATH-M35, that sound better for $50 (the drawback of the Audio-Technicas for mobile use is that they have extralong cords). While this Philips O'Neil has 40mm drivers like the Audio-Technica and a lot of other affordable over-the-ear headphones, the sound just isn't all that detailed, and the bass just doesn't have that much kick to it.
Sure, they sound a lot better than the cheap Apple earbuds that come with iPods and iPhones, but these aren't headphones that make you say to yourself, "Wow, these sound like headphones that cost a lot more." They lack the airy, more open qualities of higher-end closed-back models, and the sound comes across a tad recessed (it lacks vibrancy and presence).
For better or worse, they sound like a modestly priced over-the-ear model. That will be good enough for some people, but if you want a set of headphones with a little more spunk (or maybe "sparkle" is the better word choice), this will probably fall a little short.
As I said in the intro, it's tough to review something that gets high marks in one area and only middling marks in another. I really liked the design of The Stretch TR 55LX, but as you can tell, I was less enamored with the sound quality. That doesn't mean these are bad-sounding headphones; they just didn't exceed my expectations like the Audio-Technicas did.
At the end of the day, these Philips O'Neill The Stretch headphones deliver a good-size bang for the buck, but it's more design and comfort bang than performance bang. If you can live with that (and the bad pun ahead), they're certainly worth considering at a price point that won't stretch your budget.