I have one, the TS9 circuit, that's built into my (very fun) TSA 15 Head. For a long time, I barely used that feature. The few times I'd tried it, it sounded harsh, fizzy, cheapo heavy-metal-ish to me. I preferred just going with the head's mid-boost and generating natural breakup. Or the many tones that adding my Joyo American Sound produced. Both of which are still great to me. But a few weeks ago, I plugged right in to the TSA 15H, just for a quick grab of frustration-venting while grading [this is a family forum!] papers. Flicked on the TS9 instead of the mid-boost. And I noticed that it was a lot more touch dynamic than I'd thought. So to get the most out of it, I turned up the head, eased off the guitar volume and tone knobs to have them in play, and dialed up the TS9 to be just barely audible when string-attacking moderately. And when I dug in, there was very sweet-sounding, very responsive break-up. (It helps that the two Eminence Legend 1258's I'm using for the head have now broken in well.) Lots of texture, depth, dimensionality--and above all, that glorious Tweedish quality of break-up based on your string attack. I didn't know that the Tube Screamer circuit was that versatile and expressive! Or am I just so glad to be able to pick up a guitar and crank an amp to relieve work stress, and be the one who's in control of frustration-tones, that I'm now over-crediting the TS9?