I've found it. the best dam player there is.
http://www.clementine-player.org/ on the surface it doesn't look that impressive. but then you realizes it has a configurable global search ofyou entire libary including EVERY internet provider you've set up (spotify and
lasf.fm included). integration with soundcloud, dropbox, googledrive, and skydrive. the best "remove duplicates" I've ever seen. impressive library management tools including a separate cover art manager.
and it's playlist abilities, don't even get me started. you can open and edit multiple playlists AT THE SAME TIME! and switch between them. and they are saved in you session so you don't have to worry about saving between restarts of you don't want to. it also has "smart playlists" that generate a playlist form your library
it has great devise support too.
sadly I can't claim it's light weight.
on my system
AMD Phenom II 965 BE overclocked to 3.8
16 GB DDR3 1600
running Arch Linux x64 it clocks in at using 335MB of ram and 2%CPU with my full library loaded for searching (~6250 tracks) and playing music
VLC by comparison used about 85MB
opening a new playlist tab and adding 85 songs to it added about 10MB to the RAM usage
It's cross platform being built for Windows Linux and Mac.
the only thing bad I have to say about it is that it currently does not have support for DLNA or DAAP network shares like a minidlna media server or an ITunes share