Yes, I might be trying to juggle too many ideas in my head at the same time
What I'm basically trying to achieve is, yes, the beefiest UnRAID box, with music and video servers, possible with what I have. The thought was that if the X8SIL with the single XEON was not up to the task of transcoding, I could use it as data storage and let the dual handle all the other stuff.
Virtualization was partly just for the fun of it, but also to be able to keep a clean VM for each task and have the option of setting up additional VMs to play around with if the mood strikes me.
Quite possibly I'm just overcomplicating things. Perhaps I should just swap the MBs and build the beefiest box I can and possibly just sell off the 1U box if I don't find any use for it (and buy more RAM for the money). It's just that used Supermicro servers are not regularly available here (Iceland) and buying new is just not in my budget (a new X9SCA-F-O and a Xeon E3-1220 with 16GB registered ECC would set me back around USD 1000!) so it would be nice to be able to put both of them to work.