This is a big fake of SE. K610 doesn't have A2DP support. SE has removed it in newer versions of firmware. The only firm that supports A2DP is the initial R1CB001. And the support is very lame, but works. If you want to try to connect, in your phone, go to Settings->Connectivity->Bluetooth->My Devices->name of your PC and press connect. All the above is tested and works only with R1CB001 firmware. And that's the reason that R1CB001 is in my phone ;-). This reminds me of removed flash support from K750 and W800. May be SE will reserve Flash and A2DP only for new W-series. How weird!
P.S.: On my PC stands Widcomm 5.1.0.2700 and works good.