My collection is mostly on CD as my vinyl was played to death on cheap players and ended up replaced with CDs as they were released. I sitll buy vinyl singles mainly because they often have an exclusive b side.
CDs stored alphabetically (except for latest purchases which are heaped separately in alphabetical order till I can get round to putting them into the proper plces (which are on book shelves, CD cupboards and such like in various areas of my flat). Alphabetical and chronological - which is as it should be, that's not obsessive at all
The majority of MP3s I have are My Space downloads where bands don't have an album to buy, although occasional iTunes purchases take place where all I want is one song.
And the entire collection is on a spreadsheet which is carried with me on my Palm organiser as I have in the past totally forgotten I already have an album and have bought a second copy!
I don't always buy everything a band I discover I like has done without checking out the sound of their other stuff, the exception being Richard and Cousteau where I knew without listening that I would like the entire output (and I'm missing that Coming Home single although I have the songs).
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There's a raven in the distance, his inscription's all around you, you can't hide
https://www.facebook.com/LiamMcKaheyandtheBodieshttps://cousteaux.com/music