Multiroom Audio Streaming with ReadyNAS

You could alway do what I have done for years, simply store the music files on the Duo and use the music player on the PC to play the music. Of course you can't synchronize it so the same music is playing in all the rooms, but, that does take processing power on the server.

Another alternative is to maybe start with the Ultra 2 and only one drive, making sure that every time you add a lot of music you update your backup (always a good idea). That will narrow the gap a bit. I looked at Newegg and the Duo (diskless) is $181 with shipping, the Ultra 2 is $299 with free shipping. Considering the increase processing power and memory as well as the future expansion capability that difference is well worth it. In a few months, you can add the second drive to gain the redundancy. (Still maintain your backup). The advantage of the redundancy is so you don't have resort to the backup in the case of a single drive failure. But, in the rare case of a dual drive failure or problems with the unit, the backup is still a very good thing to have.