Transferred from "do away with desktop thread" because that thread was just a chat and I am trying to solve this.

Wondering whether someone might assist with this...

The N900 comes with a composite cable and I can find a cable that will convert the composite video-out to 15-pin VGA. The problem is that as well as an internet tablet, the N900 is a phone and a media-centre too and my monitor has neither speakers nor microphone. Therefore, my question is: how can I separate the audio so I can make/receive calls and listen to music while using TV-out?

As well as the standard Nokia ear/micro -phone with a single 3.5mm jack, I also have a headset where the sound in and out are on separate 3.5mm jacks.

All ideas welcome...

Use a blue-tooth audio device, like a headset or an audio card.

Yeah - guess a BT headset would work. Definitely an option.

What's that - a usb one you mean?

The same ring on the A/V plug is used for both video out and mic in. So, if you're actively using the video out, and you don't want to use the internal mic, then Bluetooth and USB, as suggested above, are your remaining options.

That's what I was wondering. Just to confirm I understand correctly:
Q. By plugging in the composite cable, the audio-in is disabled for the display connected to the 3.5mm port (even if screen has microphone capabilities); correct?
Q. Is the microphone built into the N900 disabled when tv-out is in use?

If the internal mic does work when tv-out is in use, then there's no problem because I will be close enough to the mic to use it in one of either normal- or speaker-phone mode. I would just need to retrieve the audio-out from the composite and pipe it to speakers/headphones.
Q. Has anyone tried this?

Alternatively, I could look for a decent BT headset. There seem to be a few HiFi ones to choose from. However, there also appear to be a number of threads claiming there are problems with various BT headsets, including Nokia's own BH-905. How amusing/annoying: searching for "bluetooth headset" in the wiki, there are no useful results, as far as I can see for the N900!
Q. Do problems for BT-headsets persist with the CSSU? And, is there any difference in problem-level between those that do/don't include microphone capability?
Q. Is there likely to be any conflict when using a BT-KB, BT-Mouse and BT headset, all at once with the N900?
- I am aware that input devices are not officially supported but I've had reasonable success with USB input.

I would prefer not to use USB-OTG for audio i/o. Apart from anything else, do Debian-armv7 drivers exist for external sound cards?

I actually had more problems to turn on the light at my desk to write this than putting the N900 with the BH-905 and my TV to tests

I am running v47 of power-kernel clocked to max 850MHz and the CSSUpdates on my device.

I use the TVout control widget to tune the output of the N900 video to the TV. I connect the BH-905 through bluezwitch widget with the N900 and started a video, which did just what you expect: Transfer the sound to the BH-905 fine.
Next i phoned home, the sound switched to the telephony application and the video stuttered a little, possibly because of too much work for the CPU, but kept playing on the TV screen, while the N900 was showing the telephony dial pad.
Next i called the N900 from the land-line, and again the video just stuttered, but kept playing on the TV while the N900 showed the incoming call.

This phone and the applications the developers had delivered are just awesome!

Indeed, this deice is truly spectacular!

Your reply pretty much answers my question of how it can be achieved. The only thing I'm wondering about is the potential interference between different bluetooth devices if a BT KB and Mouse are in use as well as these headphones.

I guess the stuttering of the video-out is something one just has to put up with.

btw. I was looking at the BH-905, the Sennheiser MM400 or MM450,if I can afford one!

And look what i just ordered http://en.store.creative.com/speaker...s/4-19979.aspx
Saw a pair of them on ebay for under €50. I may report about them if i tested them a little.

These?

--FILLER TEXT--

I'm pretty sure the N900 is locked at 600Mhz when making/taking a call, regardless of overclocking (see kernel power wiki). This might have something to do with the stutter.

What're you trying to do - watch a video whilst making a phone call? What on earth for?