Apart from choirs, I think Ar Log was one of the earliest groups to tour in N. America. Since then, there have been a number - not all still in existance. (Don't suppose anyone remembers Dim Byd Eto!) I don't suppose the primarily instrumental ones (the KilBrides, Robin Huw Bowen, et al.) would provide an answer to your question, but Crasdant seems to have continued success at N. Am. touring - they do some vocal. Don't think Plethyn ever toured - which is a pity. I would think that Bob Delyn a'r Ebillion would do just fine, but you should have a word with Stephen Rees in Bangor ...

I agree with MTed re: the male voice repetoire, although I always found that it was both the ex-pat and the no-Welsh-connection audiences which wanted to hear Welsh songs sung by Welsh people. The trick is in setting up the songs in the intros.

Rwy'n cymryd dy fod ti'n byw, neu yn dod o, Waunfawr?

sian