Is this a standard feature on all devices or just present on some devices?
Is it possible to enable/disable?
Specifically, is the feature present on the Dell Venue Pro?
I have a Dell Venue Pro and can confirm that it supports A2DP. All you need to do to enable it is turn on Bluetooth in the settings page and connect an A2DP supported device.
There is one exception, if you are playing video, the audio will not be transmitted through A2DP. This is a limitation known to the engineering team, their reponse to me was that the audio format embedded in a video file can vary from video to video, which presents a problem for the A2DP to transmit.
I also own an htc HD7, htc Titan, htc Mazza, htc Radar, htc Surround and a Samsung Focus. All of these devices produce the same result.
This forum thread mentions that all 1st gen devices could do that, and Dave Blake confirms that all Mango devices do support that.
This page from Microsoft has three 1st gen devices that mention A2DP support. I guess throwing a device name together with
specifications could help confirm if your device does, but as far as I can see all devices do support this.
This thread on XDA developers shows the registry key that configures, enables and disables the A2DP profile.
If you are able to inspect the registry this would confirm whether the feature is enabled or not, but it does seem to be enabled on most devices by default.
HKLM\Software\Microsoft\Zune\Playback\Video\A2DP\CapsSet1] "DisableA2DPPLayback"= dword:1
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Bluetooth\A2DP\Settings] "UseJointStereo"=dword:1 ;For A2DP audio quality in AKU2.3 and above. "BitPool"=dword:1E ;By default, A2DP uses a bitpool of 0x30. 0x40 - Better than Excellent audio quality 0x3A. "MaxSupportedBitPool"=dword:50 ; PTS 3.0.1 requests Max Bit Pool is 0x35.