I would just get the 1333 from a reputable brand (crucial, g skill, corsair) and call it a day. Yeah, 1600 works in some cases, but the if there is an increase in speed in would be imperceptible and possible incompatible. Eight gigs of 1333 would be all you need.
Of course this goes without saying, but if you need speed, go SSD.
+1
The speed of Ram is not your problem. For writing audio you need more memory and fast hard drives.
8gbs of ram with a firewire 800 connected hard drive is great. If you want faster get an SSD.
Teej said:In that case, what's the best 2x4Gb 1333 ram I can buy for my computer?