You can easily use this loop for a volume boost, as it is - you haven't to change it to a 'serial only' loop and you even don't need a Boss GE-7 to obtain this!
With the Send Level and the Return Level dimed and the Send & Return jacks jumpered with a guitar cord produces a gain boost of about +12dB, much more than you'd ever need for a solo boost!
So simply put a on/off switch into the guitar cord from the Send to the Return jack, dime the Return Level and adjust the desired boost amount with the Send Level - that's all
![Wink :wink:](./images/smilies/icon_wink.gif)
Larry