Bought the Syllable G18 Bluetooth 4.0 Headphones.
I might be the only one in the world who has bought these, if the web is any indicator.
USD140.00 for a set of Bluetooth headphones with no track record is on a par with buying a race horse called Bruce from a guy in a pub.
The sound quality is pretty good when paired to the XPERIA LT26i and or XPERIA M, although I don't have any 'known' quality Bluetooth headphones to compare it with.
Maybe a trip down to the local Audio shop to 'tire kick' a pair of Sony MDR-1RBT Bluetooth headphones to find out how my G18 stack up.
G18 pairs with all my Android devices without any problems. Even pairs with my Android v2.2 TV box.
Paired easily with a Sony Ericsson K610i (circa 2006) and audio sounded good.
The headphones can be paired with two devices at any given time.
There is no audio 'buzz' or breakup when testing audio frequencies from deep bass to high treble.
Seems to be good spacial audio definition too, but'll need to get a few audio tracks to discover how good that is.
The headphones use Bluetooth 4.0, but I'm not sure what that gives us beyond Bluetooth 3.0 + HS
Seem to be good for up to 8 metres with a few walls using XPERIA M.
The headphones have mics(x2) in both ear pieces and a tap on the big button on the right answers any calls.
Music fades out to take the call and continues when call is completed.
Was playing .flac encoded music when call was taken and the person on a land-phone sounded like they were talking to me through a bake bean can.
But that could be going from stereo .flac encoded audio to mono phone call quality. The other person said they could hear me clearly.
Pairing with Win7(32bit, 64bit) is another story... it's a real struggle, but it does pair.
Using 3.5mm audio connection seems to ramp things up a notch, with greater driving bass and maybe richer sound, but that may be to do with the software drivers on the originating device (PC/Audio Receiver), so that's something to investigate over time.
You will find yourself moving the headphones around a bit after an hour or two as the ears become a bit sore over time.
In short, big headphones and a good sound with an XPERIA M.
Also use a pair of Suicen AX647 bluetooth v2.1 head phones which are cheap ($25.00), but provide a good sound (lacks a bit of bass) but you can use them for hours with no ear strain and I got good signal at the other end of the house 15 metres away (approx two walls)
Sennheiser PX 100-II with over empathised bass.
Sennheiser ear-buds from my old iRiver MP3 player circa 2005.