The full size TC Spark is one of my all-time favorite pedals (I have 3). It excels at many things. I love it as an always-on thickener, especially with single coils, and running one Spark into another can yield some cool results. (I know of a bassist who uses two Sparks chained together as a bass overdrive.) I'm curious as to what people are going to add in the thread. That pedal serves me so well in so many different scenarios that I'd be surprised to find a similar tool that I would like equally as much.
I have the RC2, and have always wondered how it compares to the Spark..
I should have added in my original answer, both the Mooer Pure Boost (clean boost) and Flex Boost fit the description well. Even in mini size, they each have controls for gain, volume, bass, and treble. The Pure Boost is similar to the Spark, while the Flex Boost is gritty and is much more of a dirty boost/saturated overdrive. (But neither has that toggle switch on the Spark that makes the Spark so versatile.)
It was exactly the same way for me - as soon as I tried it, I felt like "This is IT!" And you're right about the price, too. I paid just under $100 for my first one, and when I was sure I wanted a second one, Sweetwater put 'em on sale for $49 each, so instead of one I bought two more. I see them on sale for $50-75 a lot, used. Worth every penny.
The TC Electronic VPD-1 Vintage Pre-Drive might fit the bill. It has "top boost" and "mid boost." They stopped makin' them, but I still see them quite a bit for good prices on the used market. I have the full size Spark Boost too, and the VPD-1 is a great sounding pedal, a little different than, but along the same lines as the Spark.
