Try "The Button" tube overdrive. I got one yesterday and have tried it on both my Mustang and my Sterling HS. It can go from a very light and smooth overdrive to a very heavy fuzz. It cost about $30 more than the Sansamp, but it is great! I also have a Bass-Drive Mosfet and TurboRAT. I've owned the Bass Big Muff, Little Big Muff, and RAT II as well as the various Boss, Zoom and Digitech multieffects' distoritions. "The Button" is so good that I'm considering selling my Bass-Drive and TurboRAT. But I won't. I run "The Button" into my Bass-Drive with the Bass-Drive set to Comp Cut. Excellent! FYI, the TurboRAT has a very gritty sound when run through the Bass-Drive.
I highly recommend this pedal, but here's the disclaimer. It gives me the sound I want on my Sterling HS and Mustang run through my GK rig. I think it sounds the best of all that I've tried and owned. (I've tried the EH English Muffin and Radial Tonebone Classic too.) Everyone has different tastes and you may not be as impressed with it as I am. TubeDepot will charge you a 20% restocking fee if you don't like it. I bought it on a chance that I would like it. And I'm happy. But just be aware of the restocking fee. I think that they could sell more of these if they would drop, or reduce, the restocking fee. It's the first botique pedal that I've bought directly from the manufacturer. Perhaps they all do this.
Here's a link to "The Button":
http://www.tubedepot.com/thebutton.html