I've been installing the new device for a week or so now - impressed so far, the device is silent (really, I had to check it was still turned on about 4 feet from me) when the drives are spun down and virtually silent in active operation - I can hear the fans now and the the slight rattle of the drive while my music collection copies over. I had to pause to listen as my PC is much noisier and it's a fairly quiet PC.
I've been tinkering with Synology's Audio Station package - it looks remarkably like the offering from Sonos and probably a string of other packages. I suspect it is going to struggle with my 145Gb of MP3 files because the reindexing of 2 tracks was distressingly slow but we'll find out. The biggest disappointment is that I think we'll find out a lot later than I might have expected as the file transfer speeds are sitting around 15mb/s - the started at close to 30mb/s which would be ok (but only ok) but now the DS213's CPU has hit 100% and the transfer shas dropped horribly - I can transfer else where at higher speeds and the lan is not busy. Have raised a support form with Synology because they are promoting much higher transfer speeds and this is a worry for day to day use.
The other problem I have at the moment is that I've added a second user and I cannot figure out how to grant that user rights to their own home folder which is a pain, fine for me.
I suspect that these are just niggles as so far everything else is looking good and normal disk performance for the odd file looks great - it's possible that I'm overwhelming the cache on the drive and the caching capability of the device is non existent but that's still slow.