Blue Heron is a high-endy early music-oriented vocal ensemble based in Boston whose members have sung with the likes of Sequentia and Chanticleer and whose work has been written up by Alex Ross in The New Yorker. But, even though Blue Heron employs some beautiful singers (notably the iridescent tenor Jason McToots and the beveled-edged baritone-bass Paul Guttry) the group's makeup confuses me.It's mixed gender, but o…
