Summary: I can't believe there is no review on this headphone. I will write a brief one because I am really not equipped and skilled to write reviews on this forum as deep and broad as other reviews resulted from extensive tests and auditions.
For sound, I could only compare this one with its wired cousin HD650. I connected them to the headphone jack on an old receiver. I listened to various or materials, classical music, pop songs, R&R, vocal and instruments.
Summary: I suppose you could get a much better experience with a wired headphone, but for a wireless set, these cans have the best sound you will find. The headphone is very comfortable. The only time they felt too warm on my head was when I was vacuuming the house. Setup is not my bag, so I called the Crutchfield tech number and a really nice and very patient guy walked me through it. I have couple of big issues with these head phones listed under the Cons below.
Pros: I use my headphones mostly for watching movies in the evening when my wife has gone to bed. The sound quality on a Blu-ray movie is pretty amazing. Super comfortable and easy to use. One thing to keep in mind as I have found, the sound you hear is only going to be as good as the sound quality of what you are listening to. Blu-ray and high quality cds will sound incredible. Old analog recordings are going to sound like... well, old analog recordings.
Cons: Drops and clipping.... Very frustrating. My wifi is near the headphone base and it does affect the headphones. It clips, and clips, and clips during a movie. I turn off my wifi and no more clipping. I'll have to see if it will help by moving my wifi router. The drops will always be there, but I can live with them. They only happen when I go to the other end of the house and have a couple of walls between me and the headphone base. Usually, I'm right in front of the tv...
Summary: First set had to be returned because the headset would not turn on. Customer service and tech support were fantastic and sent a second set right away with return shipping label for the bad set. Second set worked great following the charging cycle. I use these for TV when wife is sleeping. They replaced an older set of cheaper Sennheiser phones that for some reason started picking up a lot of static. Maybe bcause of age of batteries.
Pros: Great price at the time. Great customer service. Fast and free shipping. Great sounding headphones with no interference.
Summary: The sound is very close to HD650 and it's very comfortable to wear for 2 hours in a row. Not it's coming to the wireless part. If I am in the same room as the transmitter sits in there is no lose or drop of signals. If I am blocked by two walls I experience lose or drop of signal and I may also hear distorted sound. Many of the low ratings on this headphone on other sites are related drop of signals.
Pros: sound quality and comfortable to wear.
Cons: Signal transmission need improvement and awkward on-phone controls.
Summary: Sound: The sound is fantastic, but I was expecting a lot more. I am currently using a Sony Pulse Elite wireless headphone. I set up my TV through the Turtle Beach DSS2 DAC to receive optical sound from TV and output it through the 3.5mm to the USB transmitter for the Sony Pulse. It gives me a really good sound but it doesn't run very long after charging so I decided to buy the Sennheiser RS 220 as a second option to use when the Sony Pulse is being charged.
Pros: 1) Very good sound 2) Fantastic build: really easy to set up and even easy to re-package. All materials feel like really well made. 3) Very very comfortable: no problem using for hours on end.
Cons: 1) Sound quality could be improved considering this is coming from Sennheiser 2) Audio drops if there are interference, probably bad if you are living in apartments 3) Cannot use it while traveling, would have been nice to be able to use it with normal 3.5mm wires.