Building tubescreamer into a feedback loop of big muff

[Venusblue]

Are there any sound clips of this? I checked youtube for modded big muffs but didn't see it, i'm real curious as to how it sounds... Can anyone explain what the feedback loop really actually does? I don't get it. It just feeds signal back to the start in order to get fuzzier, basically?

Also what happens if you put a big muff in the feed back loop of a tube screamer?