The OBEL merely allows you to have a master volume control on the guitar - after the effects. And you can bypass the effects loop. But the OBEL in and of itself has virtually ZERO to do with the sound and tone of the MuTron or Qtron. The advantage is that your guitar signal is always hitting the 'Tron with full signal. If you don't have an OBEL, then a volume pedal placed after the effects is the next best thing as it gives that master volume control that's pretty important when using a 'Tron and finding the right volume.
Adding all these other suggested boosters and devices seems like adding more crap to the setup as a band-aid. When it's all working right there is absolutely no need for extra booster devices.
The MuTron and Qtron are very sensitive to bassy notes and less sensitive to high treble. So for the Jerry Mutron sound, it seems that the middle pickup set to single coil is the perfect voicing and trigger for the Tron for things like Shakedown, Estimated, Fire on the Mountain, etc. The true art is in the right hand picking control. Again this is where Jerry puts everyone to shame as his picking dynamic control was at a level of mastery very few guitarists will ever attain. The MuTron is a tricky effect, requires extreme pick control and very careful coaxing of the right kind of tone from the strings to make it open and close smoothly and nicely.
If the MuTron isn't opening up with these simple things; middle single coil pickup, guitar volume cranked, guitar tone knob wide open bright, correct guitar pick, Mutron's "gain" set to nail the proper trigger threshold - then maybe the pedal does have a problem.
In my 30 years of using MuTrons for Jerry's sound, I never found a Strat or Jerry-ish guitar that wouldn't easily drive a MuTron to get that proper sound. And also consider that when Jerry started using the MuTron, his guitar did NOT have a buffer in it. He actually ran passively from his guitar straight to the MuTron. I don't think it was until 1978 that he had the fully buffered OBEL installed. Point is, the Jerry MuTron sound doesn't require a buffer, never needs a booster, doesn't need the OBEL, just a good picking technique and the right pick and pickup setting. The buffer/OBEL setup is great, but not required.
... and it's just like any other day that's ever been...