Aye but being a Paladin if my guild was trying to decide this I'd sacrafice my rights to a good Bard.... I like that Bonus more then Mana Preservation.
Depends, though. A bard with epic has no use for this (singing modifier on this is 1.4, epic is 1.8). A bard planning to stop wielding their epic is probably going to have access to better; Abalone Engraved Tribal Mask, or Crowned Staff of Anguish. Though some such bards may choose to go for it. Any bard planning to ditch their epic must be in Elementals, essentially, because before then, it's not possible to acquire all 5 instrument mods at at least 1.8.
And just to contradict myself, I'll note that singing mod is a pretty rare one, and off-hand, I can only think of those other two items I mentioned, that have one, besides the epic. On the bardic side of things, very much a matter of personal choice whether or not you would want this at all. Pre-epic, it's uber. And it might be somewhat useful for replacing the epic's singing mod.
As for myself, I would rather have given it to a non-epic lower level bard, or to a lower level of one of those other classes. I don't foresee ever actually wearing it. But, since we couldn't find it listed anywhere, I needed to test the mod on it.
This seems to be a nice bard item, but unless you dont like wield bard epic ( or if you dont have it for some reason at this point ), this would go to someone else.