"a niggle of critics"
"a box of accordionists"
"a capella of unaccompanied singers"
"a bismal of banjos"
LMAO! ยง:-D
How about these?
a smut of rappers
a staggering of pub singers
a contrivance of teen pop divas
a trocity of bodhran players
a gumbo of Zydeco musicians