TS Clean Blend control

[SonicVI]

Sorry, I know there are older threads covering this somewhat but I can't search for them now.    I'm building a Tube Screamer and I want to add a clean blend knob for when I use the pedal with bass (along with a couple other mods).   From what I gather the most effective yet simple way to do this is to tack use a pot which pans between the TS input and a simple single transistor or op-amp buffer (one of the "basic buffers" from AMZ or Orman, I forget which) with a gain of 1 for the clean input.  If this is correct the buffer is being used mainly for changing the impedence of the clean signal to keep the TS circuit from loading it down,  rather than boosting it, right, because the gain is 1?