The more I listen to Sarah Rabdau & Self Employed Assassins, the more I hear the pop undercurrent that flows beneath their adventurous arrangements. There’s a lot that goes into their sound—so much to take in. Couple this sense of layered artistry with an engaging live performance and you have a show to remember. Like this past Friday when Sarah Rabdau & Self Employed Assassins released Free as Thieves at TT’s…