ACS T-15's IEM's (In Ear Monitors)I purchased these monitors as solution to plug straight into my existing ER-25 custom molds, rather than purchasing a separate molded IEM solution.I have been using the ER-25's for a long long time now and rate them very highly. I will admit that they do take some getting used to and I do miss loosing alot of of my guitar tone, but I only have one pair of ears and I am conscious of the amount of damage I probably already done to them over the years, so protection is the only way forward! I am also on a bit of a personal crusade to get musicians, concert go-ers, sound engineers, bar staff etc to protect their hearing. I am an advocate that great sound doesn't have to be so loud people in the audience are in pain. Turning things down is a much better solution to getting better than turning everything up and up and up.I am not wholly convinced by the robustness of the cable, I think that the cable on the Shure headphones for example, is much better. Although (and I don't want to tempt fate!) I have treated some feeble iPod headphones badly over the years and they still work fine! The cable is Kevlar reinforced cable that so it should be durable, it is probably my own preducice and gut feeling that is the issue here, the other positive about this is that this material seems to keep cable noise to a minimum. I just would have thought for the cash they would be a bit thicker and more positionable, I.e. So you could wrap them behind the ear. I guess this brings me to the point about where they seems to fit into the market place, are the simply audiophile headphones for those with iPod's etc who want to go on about how much they spent on headphones etc etc etc and the Kelvar lining etc etc etc or are they headphones for live use. To be honest I am unclear, I used them with my iPod (and the ER-25's) it sounds great to be so isolated, but the sound was very top heavy and lacking in definition. I think I would have been very disappointed if I had paid that much for them to use with my iPod! But they perfectly did the job for live use. Having said that I do feel that I potentially could have got away with a cheaper option, given the noise of the environment and my requirements.The fact that they are the partner for my ER-25's was the main selling point, but I could also fit my cheap Sennheisers in there as well, albeit with not such a good fit. But during live use, I did have one of the headphones pop out of the mold almost straight away, which was a bit worrying, but after that they were fine. I potentially could glue the headphone in, but then I loose the ability to use the ER-25's.The sound was great for live use, I have a monitor mix which simply adds in the bits missing from wearing full on ear plugs at a sensible level, in this case I would say everything over about 7-8KHz and a little bit of a boost of the guitar level so I can hear what I am playing.Pros

Good sound quality for live use
Comes with a case

Cons

Concern about the robustness of the cable and the headphones as a whole.
Not convinced about the sound quality when listening to audio.
Seemingly expensive for their perceived quality.

I think I will have to comeback to the review after I have been using them for a while. I am not returning them, but I think when you look at the combined price of the headphones and the custom ear molds I think I would have liked something which inspired more confidence in the product. They are for live use, and we all know things on the road are pretty tough on gear, flimsy stuff just doesn't last long. We shall see.Total 5.5 out of 10PeaceNeil