The Soundman OKM II microphones are truly excellent binaural microphones. So far, I've recorded street ambience, a choir in a Cathedral and done some nature recording with them and have been really pleased with the quality of the results. The noise floor is slightly noticeable for extremely quiet nature recordings (as you might expect) but, in practice, when playing back the recordings in a real-world environment I find it acceptable. For louder recordings, even for quiet street ambience, the noise floor is barely noticeable. I would, however, definitely recommend getting the Soundman windshields to go with them to avoid any wind interference and I have been using them with the A3 XLR adaptor. This set-up has given me great results free from wind noise and full of clarity and immersive directionality.
I bought these to get portable binaural recordings using my own head (I'm an artist and like acknowledging the presence of the sound recordist) and this set-up is perfect. I can walk around surreptitiously capturing audio that sounds extremely close to the sounds my ears capture. The Soundman mics are great for capturing the body sounds I want (footsteps, clothes sounds, deliberate breathing) and are good for excluding the sounds I don't want (pulse, unwanted breaths, swallowing, etc.), so I can choreograph my own movements to emphasise (or not) my own presence during the recordings according to what I want. The frequency response, to my ears, sounds very open and gives an accurate representation of traffic rumbles, high bird calls, and literal airiness as the wind moves through trees, etc.
Especially for the price, I would definitely recommend them to anyone interested in binaural recording or for simply and easily creating high quality ambient recordings. I've already had lots of compliments from sound recordists and others on the recordings I've made with the OKMs and I've only had them a few months! These seem to be a popular choice for theatre (and other) sound designers and I can see why. I also believe these do extremely well compared with the Neumann head (which isn't as easy to walk around with as your own head!).
