Does the personal tribute effect Concerto (+.2 mod to all instruments) stack with worn instrument mods? Normally I would assume no since multiple worn instrument foci don't stack, but I don't know if Tribute is implemented differently than worn items.
Don't waste your tribute slots on mod to instruments. Group gear or raid armor will get you high enough.
Tribute effects are worn modifiers. Use Fury of Combat, Eyes of the Hunter, Second Chance Your pick for the last two - I go with +hp Strength of Body and Strength of Body II. Others use +mana things or +ac things or +herostats things