In this video I take a quick look at the Legendary Tones Caswell mod—Tim Caswell’s flavor of “that” hot-rodded Marshall thing—except it’s a plug-in module that drops into a preamp tube socket. I’m not getting deep into install here (I’ve got a separate video for that), so this one is straight to the point: before/after tones, real settings, and what actually changes when you add the module. For a limited time, these were shipping with an upgraded NOS Phillips 1287 tube, which is normally a paid upcharge. I demo it first in a Marshall Studio Plexi/SV20-style setup, guitar straight in (Charvel San Dimas with a Suhr Aldrich bridge), no boost, and I keep the amp in that “stage usable” middle ground where you still have room to hit it with an OD later. With the Caswell, I’m mostly living around 9:00 on the module gain—thump on, bite off—and it just brings the heat: tighter, more aggressive, and more powerful than simply cranking the amp’s loudness controls. The bite switch adds a big upper-mid spike the amp can’t really do on its own, so it’s a balancing act. Then I move to a Ceriatone JCM800. The 800 already has gain, and with the bite on + stock bright cap it can get a little too messy, but once I bypass the bright cap the bite becomes a really useful, different kind of cut. Bottom line: if you want more gain/thump/cut without soldering, paying a bench fee, or permanently modding a valuable Marshall, this is a solid, reversible way to supercharge the amp.