You don't need FreeNas to create a shared folder!! One of the primary reasons a NAS would appeal to most people is so they don't need a computer running all the time. NASes use less power, are quieter and cost a lot less than even half the 32GB system memory you are talking about.
If you are going to build a NAS of that calibre then it totally and absolutely defeats the purpose (for music serving purposes anyway - don't know what else you're doing with it). Most music servers can access a simple Windows/Mac/Linux share directly from a computer, and if leaving a Xeon workstation running 24/7 was an appealing option then a simple shared folder is all most people need to do.