I've got a Zoom MS-70CDR [multi-effects] pedal, and a few people are saying not to use it via an aux send and return, owing to a comb-filtering issue. Have you noticed this issue with digital pedals on aux returns?
The 1973 version two Big Muff Pi — with a ram's head printed on the casework — was used on so many classic records that EHX have decided to bring it back.