Sennheiser On-Ear 900MHz Wireless RF Headphones

I've been using these for a year and a half now. As far as the quality of sound aside from interference, it stands up decently well against studio monitors. The sound is excellent. The batteries have behaved well too, they can hold a charge for a good 8 hours for me (and I don't leave them on the transmitter/charger after they charge, it's not good for batteries). The durability of the parts is great too--I've dropped these a good number of times and the most that's happened is one of the pads has come off (and I just lock it back in place). The reason I know about the durability though is one of the unit's many drawbacks, most of which are design failures that would likely embarrass any engineers with a sense of pride (ie. most). It comes across like Sennheiser focused more on speaker quality than most other aspects, and while the speakers are great the ergonomics of these headphones for example are awful. I've had to basically 'train' them by bending them repeatedly to fit my head adequately (by default they squeeze my ears enough to ache after about 20 mins of listening, which is unacceptable). I have a pretty average-sized head by the way, at least according to hat fittings. The overhead portion of these should have been built to be adjustable/bendable, and they are not: there are only notch-based length adjustments near the earpieces. They also slip off most of the time if I tilt my head forward, and they have always done this (before and despite any of my adjustments). The result is usually hitting tile after dropping from head level, and usually one of the pads flies off. All it would have taken would have been some time spent wearing these to realize the flaws here. The other issue I have--and it actually makes me avoid using these a lot of the times--is a design feature that comes across once again like it was never tested. The transmitter/charger is designed so that if there's a sustained period of sufficiently low amplitude/volume in the signal (2 minutes) the transmitter *stops transmitting*. The logic behind this decision still baffles me, because it doesn't serve any purpose like saving battery life because the headphones stay on. What's worse by far though is the result--I'll put together a playlist at my system, start it up, put the headphones on, and go about my business (usually chores around the house that music makes more tolerable). If I remember to keep from pointing my head down and dropping them then all is well until the volume of the music drops below ~15% (at the end of the set, on some songs that have low output for portions of them, or if I have to pause for some reason). What happens is that after two minutes of silence the transmitter stops and I get full volume static in my ears. You can imagine the jolt that gives someone at least, it prevents me from ever putting volume above 40% for any length of time, I can't play some low-output music I own with these, and all the time I have them on I'm fearful in the back of my mind of the signal dropping below 15%. This design flaw is *inexcusable*, especially at this price point. All it would have taken is some measurable amount of testing. The last issue I have is because of yet another lack of testing--transmission/reception. The frequency band of adjustability at the headset seems fine, but the transmitter's band is far too narrow, so the signal is more susceptible to interference in an average environment than it should be. The power output of the transmitter is too low as well, so even close to the transmitter there's audible (very low but still audible) static, and if I wander more than a room away from it the static starts getting in the way of the music. These types of flaws are not acceptable to me. It's not hard at all to design reasonably according to use, and Sennheiser puts this unit at a price point where there is absolutely zero excuse not to. The result is unnecessarily overpriced, sub-par functionality. Update: a few months after writing this, and the internal battery is now losing charge life. After only an hour or so of listening the battery dies. It's obvious that the battery type chosen for this unit was substandard. Overall, these have become not only one of the most expensive pairs of headphones I've owned, they're also the most poorly designed and manufactured. I am getting more use out of my $20 specials now, and I'm debating digging up my old monitor headphones.