Rumble 40 or Rumble Studio 40?

[skydvr]

There’s a thread here discussing that exact thing

Zoom b1 4 or B1X 4

Would I be best to buy the Zoom B1 4 or the B1 4X. Also it seems to me that I saw somewhere that it was best to connect it into the effects loop of my Rumble 100. Can someone confirm this and tell me why?