My main amp is a Fender Mustang III, not sure what that makes its loop, guessing series but it’s just a guess. I have never seen anything about it being buffered.
The issue is that basically the FX Send signal when gain is up (for dirty sound) is significantly higher/louder than the output of the pedal even at max volume, the the pedal gets drowned out.
I can’t put the pedal in front of the amp because I use the amp’s distortion. I’m guessing it would work fine with the amp set to clean, the dirt coming from an overdrive or distortion pedal placed ahead of the BB (BB last in the chain, straight into the amp input, not the FX chain). I’ll give it a try but I don’t get the same tone from my cheap overdrive pedal than I get from the amp’s distortion.
When I connect the pedal via its headphone output to the Aux In of my amp, I get more or less the same loudness. I haven’t plugged the headphone out in the FX loop, I need to scrounge for an adapter. It may work, I have plugged in an Android tablet with a drum loop program in the FX signal chain (through a small mono mixer) and I don’t recall having volume complaints, just that it’s a pain to deal with a tablet.