0_o, sounds a little like vandalism. Anyway, device will work with just one speaker, but, as N900 is stereo device, You'll be downgraded to even less than mono - a 1/2 of stereo channel. Don't try listening anything like properly mixed ogg or flac.

Anyway, I don't see much reasons for such "demolition" - after all, instead of soldering small USB port to original pads, You may insert same port here, but connected to tracks via cables, and kept in place just like speakers or audio jack - it will be prone to any breaking.

You don't gain *anything* by full-sized female port - y-cables or adapters are cheap and easy to made, resulting in more flexible setup, without sacrificing anything.

/Estel

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If You follow this Community, you know that I'm dedicated modder myself, but I wouldn't demolish my device like that, just for sake of it. Of course, decision is up to You.