A used Dirty Haggard Audio SQRT Distortion Sustainer in Very Good condition.

FROM DIRTY HAGGARD AUDIO:

The SQRT is my take on the old Russian pi's. I tightened up the low end a bit, reduced the range of frequencies being clipped by the first distortion stage, and I added the popular 'shift' control which effectively acts as a 'fat/thin' control in addition to widening the mid-scoop.  This circuit does have some of the normal DHA tricks to reduce noise, but it is NOT gated like most other designs!