N900: 3.5mm jack, 4 contacts to 3 contacts adapter?
 

I noticed that the headphone that is included with the N900 has 4 contacts (the output jack has also one Video channel):

Do I need an adapter like this one:
http://www.amazon.de/Headset-Audio-A...=27O4BBG2ZAFR6

or can I simply plugin usual 3 contact 3.5mm headphone jacks?

(I want to use my usual headphone...)

Re: N900: 3.5mm jack, 4 contacts to 3 contacts adapter?
 

You can simply plug it in. TRRS (4 contacts) systems are compatible with TRS (3 contacts) ones.

Re: N900: 3.5mm jack, 4 contacts to 3 contacts adapter?
 

That adapter is also 2.5mm -> 3.5mm. Totally useless for N900 which already has 3.5mm port.