The Sonictron 9001 lets you play almost any Sound/Musicdisc in vanilla Minecaft. It plays up to 64 of them, as soon as you apply Redstone (or rightclick with the mobile one), at a rate of 1 Sound per 1/10sec. So compose your Songs by just clicking around in a GUI. It loops the Sound as long as Redstone is applied, so you don't need a Timer.
The mobile Sonictron can store the Data of the Sonictronblock by just right-clicking the Sonictronblock. If you sneak-rightclick the Sonictronblock with it, then it writes whatever is stored on the mobile Sonictron to the Sonictronblock. The Dataorb is also capable of doing that, but it can't play the Music.
There is currently a major bug with this item, as it will not produce any sounds whatsoever in multiplayer, EXCEPT for all music disc varieties. It also reacts badly to redstone current provided from Redpower such as alloy wire—somehow causing it to continue to receive pulses even after the source of the current has been removed.
It is also difficult to remove this block without breaking it into machine parts once placed. However, persistent shift-right-clicking with a tool such as the Omniwrench will eventually succeed.
Music Disks Vanilla Music can be played in the Sonictron regardless if you have the disk or not. You do not use a disk you have found to play music, but instead, left click until you hit the music disk icon on the staff (Will be C418 - cat). To change the song, right click the disk.