if you can afford it, get the 6 core 4930, which is what JC mentioned at the top of the thread... it's probably still $500 buckeroos but man, is it a screamer! I spent a lotta time lookin' at cpu's, and the two above gurus thoughts plus outside forum data and finally went the the 6 cores/12 threads. You'll have to wait till 2015 ish for haswell to hit that mark...just google the two choices and spend the night digesting it all or remember, it was at the top of this page...
furthermore, why not have jc or jim build it? it'll be tweaked to the max and trouble free...well worth the bit of premium for truly stellar, matched components not to mention proper setup...which makes all the difference in the world. You won't be in here complaining about glitches/problems that really get back to the setup/computer build itself... I can't begin to imagine the amount of forum time spent on trying to resolve folks problems that often get back to component selection/configuration/setup...or what I've come to routinely call cheap china sheeet thrown together to maximize profit margins...
time/angst/frustration/inspiration lost, let alone the value of YOUR time trying to sort it out (good luck!)...avoiding that is worth way more than the small price for the specialized skills and experience that'll go into creating your daw...