There is a profile on recon in which he both acknowledges being Dirk Caber, and saying that his tuba weighs 35 pounds. I've read other profiles which lead me to believe that is primary musical interest is composing, rather than performing, but I seem to recall that in his Dirk Caber persona he's done fundraising for the Big Apple Corps (which is a gay/lesbian concert and marching band formed in 1979, and still going strong).