I'm not a music producer but audio is important to me so I have been dragging my now old Xfi Fatal1ty edition PCI audio card from motherboard to motherboard. I find the hardware accelerated audio and Creative audio tools to be much better than the onboard.
My choice of motherboard was the EVGA X58 SLI motherboard because with two 295GTX video cards in SLI on two X16 PCI-E slots I still have room for my old PCI audio card and my PCIe captureboard. Some motherboards block the PCI slot when doing SLI
yea i am aware of the space problem with SLI cards, but that is why i need a motherboard with great onboard audio so that i don't have to by a bigger or more expensive mobo just for an extra card slot.