The Stax SR-207 model may be the brand's least expensive full-size headphones, but the sound is competitive with far more expensive reference-quality dynamic headphones.
The Stax SR-207 electrostatic headphones don't sound like other headphones. They're more open, so the sound is less stuck between my ears. Listen to a pair of SR-207s for even just a few minutes, and when you switch over to AKG, Grado or Sennheiser headphones they'll sound "canned." The SR-207s' unforced presentation really comes into its own with well-recorded acoustic music, which sounds more acoustic, warmer, sweeter and more natural over the SR-207s than my best dynamic headphones.
Stax's flat, thin-film electrostatic drivers are much larger than the dynamic drivers found in conventional headphones. The company has a long history of making electrostatic headphones; I owned a pair of Stax Lambda Pros in the 1980s, but Stax started making electrostatic headphones in 1960 in Japan.
The thing you have to understand about transparency, or clarity, is that it's all relative. That is, you might think your headphones are perfectly clear and clean, until you hear a pair that's way ahead of what you have. That will surely happen when you don a set of SR-207s; the clarity gains won't be subtle. There's so much more detail, but I wouldn't characterize the sound as bright.
So the SR-207 model is perfect? No, play the Black Keys' raunchy blues rock at maximum volume and the tables turn: the SR-207s' bass oomph comes up short, and dynamics lack the kind of impact you get from an Oppo PM-1 or Grado RS-1e. Again, those two models can't touch this one for clarity. I'm not saying the SR-207s can't rock out or make bass, they absolutely can, but they're not for headbangers.
Comfort is another strength of the SR-207s: they're lightweight and the earpads exert little pressure against your ears, making them one of the most comfortable models to wear for hours at a time. The design is open-backed so you can hear external sounds easily.
There's one big caveat -- these headphones can't be plugged into a conventional 3.5mm or 6.3mm headphone jack. They must be used with an electrostatic headphone amp. But the good news is that they do come with such an amp, called the SRM-252S. It has analog-only RCA inputs and outputs.
The Stax SRS-2170 Basic System includes the SR-207 headphones and matching SRM-252S amp. The price is $790, including shipping in the US. In the UK it's £750 and it's AU$1,299 in Australia.
So sure, the SRS-2170 package is pricey, but it's Stax's least expensive electrostatic headphone/amp system, and the most affordable electrostatic system I've ever tested.