I tried it, I liked it and I like to try it again!! I would prefer the metrowest area but I will incall into Boston!!

Try the conservatory or the US Marine Band !!!

Urban Dictionary differentiation of Play the Trombone

http://www.urbandictionary.com/define.php?term=Playing++the+Trombone

WikiHow Differentiation of it

http://www.wikihow.com/Play-the-Trombone

If she tells you to straddle her face gets out the lube and starts stroking your cock while giving you a rim job I would guess she is proficient.  However this is just an educated guess.  If you let your hands wander down on her and play with her pu**y I am guessing you may have some intense music.
My advice, find yourself a submissive provider, that does incall and you will be well on your way to achieveing what you seek.  Or you could always call the provider you did it with originally.