It sure is interesting, having several DAs lying about. The M-72 and S-73 promised to be similar. My assumption was I'd mod the plainer S-73, add a Bigsby and HB sized single coils, to push it surfward. While the beautiful and sweet toned M-72 (chambered mahogany body with thin maple cap and Goldtone HBs) would stay stock. It's not turning out that way. The M-72 does sound sweet. With new pots and caps, even better. The surprise is that the S-73, same pickups, but a simple mahogany plank much like the old Guild S100, has something the other doesn't. Stock everything, bridge tone pot non-functional. Doesn't matter. It sounds like an acoustic unplugged, sort of thin but bright and loud. Plugged in, the bass is perfect, the balance bass to treble is perfect. A propensity to wail when you dig in, cleans up when you back off. Ever play a guitar that has it? This one has it. So the plain jane S-73 goes untouched. The M-72 will get the B5 Bigsby (using a Vibramate, no holes) and Z-90s. For the sake of tone science.