Two-stage JFET Booster does not work when feeding other pedals

[highwater]

I have two sequential JFET boosters ala http://www.muzique.com/tech/bipolar-j.htm (the second schematic) on a breadboard. The second stage has a bypass cap on the source, the first stage does not (the only change from AMZ's schematic).

I'm at my wit's end here - it sounds great by itself, but makes no sound at all when I put a pedal between it and the amp (a Crate G-10 at the moment, but it's also previously worked with a borrowed Vox AC4TV).  If I run the input jack straight to the output (leaving the two grounds still connected to the circuit) it works fine even with a pedal, so I know it's not the patch cable from the pedal to the amp. I've tried a TC Hall of Fame and (to make sure it wasn't just some finicky DAC bullcrap) a Morley Bad Horsie 2, and I get absolutely nothing with either of them - not even in bypass (The HoF is set for true-bypass).

What the heck is going on?

[highwater]

Update:

In a fit of sudden post-posting inspiration, I pulled the power-supply-filtering-bit (R9 and C4 in the schematic) out and ran the battery straight to the power rails - my DMM only reads 1/10th of the battery's voltage with a downstream pedal, and as it turns-out, the battery reads as almost 0v with the filter cap-and-resistor there.

So it seems like a downstream pedal is somehow sinking all the current it can get from the battery on the breadboard... and now I'm even more confused than I was before. I'm powering the breadboard with a battery, but the pedal"board" is fed from a one-spot - I only have one 9v battery at the moment, so I can't check with a battery in the actual pedal.

[highwater]

So... the output ground was shorting to V+ through a 100ohm resistor from a different circuit on the breadboard. I've been pondering this for almost a week, and of course, I find the dumb mistake as soon as I ask for advice. Murphy's law: 1, me: 0.

But this begs the (probably more interesting) question - why didn't it matter without another pedal downstream? Shouldn't it have buzzed like crazy when it *did* work?