The N900 does have an 3,5-mm-stereo audio-jack.
It is no problem to connect it to an amplifier..
And i would like to have a Sequencer link Sunvox on a N900 instead on a netboox becauce ha allways have my phone with me..

I think the Sunvox should have a chance..The sunvox gui on the n900 should be much better than the iphone version because the n900 has a much bigger screen resolution..
the Tracks made with it sound very promising..