I've had the pleasure of seeing him live at Mezzrow a number of times, and 1. His sound is totally dry, and the room is so small and full of people that there's very little perceptible room sound. If he at all cared about reverb that would be a place to use a pedal, but he doesn't. 2. The amp is very quiet and he plays quite acoustically lively archtops, so there's some acoustic top end that gets blended in with the dark amp sound. Last time I saw him he was playing a beautiful old non-cutaway L-7, and I feel like I could hear the acoustic sound just as much as the amp.

I love his tone. I feel like it emphasizes the bounce in his playing that a bright sound wouldn't as much.