(I've been constantly receiving questions about all these questions on
various Pocket PC boards and newsgroups; now that I'm tired of answering the
same question at least five times a day, I've decided to dedicate a complete
write-up to it.)

I've published several articles on A2DP and AVRCP (please see the Bluetooth
category in the Smartphone & Pocket PC Magazine Expert Blog), which is a
great way to listen to music wirelessly in (almost) Hi-Fi quality and
stereo.

The "traditional" headset mode, on the other hand, may be much more useful
for much more Pocket PC users because

a.. There are much more cheap, "traditional", mono Bluetooth headsets than
expensive and bulky A2DP stereo headphones. They are available in all phone
shops everywhere and are used by, it seems, everywhere. An example of them
is the X3 micro, of which Jack Cook has just published an excellent review
b.. To listen to, say, GPS navigation, the (not very good, phone-grade)
quality of these headsets may be sufficient
c.. Furthermore, they offer two serious (!) advantages over the A2DP mode,
because of which you may want to go for the traditional headset mode instead
of the high-quality A2DP mode even if you have a full-blown A2DP stereo
headphone:
1.. when you actively connect a headset device to your PDA, you will not
only use the PDA-to-headset sound routing, but also the opposite direction.
That is, if you, for example, want to use your PDA to record your speech
(and that of your environment), and the slightly degraded (recording) sound
recording quality (which won't really be an issue when you only plan to
record speech) isn't an issue, you may want to opt for using your headset to
record your speech as opposed to your PDA, which, then, can even be in your
pocket or even in your suitcase.
2.. the CPU usage of the "plain" PDA-to- headset unit will be about an
order of magnitude less than that of A2DP. For example, on the
non-overclocked HTC Wizard, device.exe consumes between 28 and 35% with
A2DP, depending on the quality. With simple non-Hi-Fi / non-stereo sound
routing, device.exe doesn't consume anything at all, compared to the default
(sound isn't routed) case. That is, when battery life and / or
responsiveness is of paramount importance and the heavy sound quality
degradation / lack of stereo, you may want to prefer the low-quality, mono
but non-battery-consuming headset mode to high-quality, but heavily
battery-consuming mode, which also makes your Pocket PC much less
responsive.

Being able to constantly (!) route the sound of your PDA to your mono
headset, first, depends on the maker of your built-in Bluetooth stack. In
here, Widcomm / Broadcom users (Widcomm is used in most PDA's with operating
systems prior to WM5 except for the Phone Edition models of HTC; as far as
WM5 models are concerned, all Acers, HP iPAQs have sticked with this stack;
the majority of Fujitsu-Siemens Pocket PC's (except for the T8x0) and all
Dell Axims (which were all Widcomm-based in the pre-WM5 times) have switched
to the Microsoft BT stack), as usual, have a lead because they don't need
additional hacks / third-party applications, as opposed to the Microsoft
stack.

more at:
http://www.pocketpcmag.com/blogs/ind...&c=1&tb=1&pb=1

--


--
Werner "Menneisyys" Ruotsalainen - Microsoft MVP - Windows - Mobile Devices
Please see the Pocket PC Mag Expert Blog (including mine) at
http://www.pocketpcmag.com/blogs/ - you will definitely like it.