Does the set bonus only work for specific PrE? For example, according to ddowiki:
Spell Singer (Brd)
Shiona's Pendant - Necklace: Superior Potency VI, Wizardry VI
Shiona's Seal - Ring: Charisma +6, Exceptional Dexterity +1, Incredible Potential
Set Bonus: 2 additional Bard songs per rest
Does this mean a Virtuoso or a Warchanter putting on Shiona's Pendant and Shiona's Seal will not get 2 additional Bard songs per rest?