I've seen a lot of references to the Mesa Diesel 115 (and 215, for that matter), being "extremely similar" to the TL606. Does anyone know what the real differences are? It's easy to see that the port cover is removed on the Diesel's ... is that the only difference? What effect does this have on the frequency response? I'm thinking of building a TL606 cab, and modifying it to the Mesa Diesel spec's.