I've tried using iTunes but I seem to be incompatible with using it. iTunes frequently gets me into a state where I lose my temper with it, both on the PC and a Mac.
Somehow it just doesn't work as I expect it to or it spends much too long thinking/selecting/doing a job and I lose my temper with it.
All apple software has that effect on me and I'm famed for saying F£&king Apple.
On it's good side - I do have 1.3Tb of audio files all on a pair of NAS devices connected via a gigabyte network accessed by a hex cored computer with 24 Gb of RAM.
My Calibre library is on the same NAS and has over 35,000 books (some of which were legally purchased) and take up 84Gb of storage and Calibre responds more or less instantly.
If only somebody would take the source of Calibre and fork it to Calibaud. Sadly, that it beyond my capabilities.