I'd not worry too much about an 'audio interface module' - they aren't necessarily needed
first: try the individual modules
if you get clipping (unwanted/unintended distortion) then try second: if your audio interface or mixer has a pad function try this - otherwise try passive attenuators or vcas (you hopefully already have these, but if not attenuators are inexpensive)
if you are still getting clipping then try third: output modules - the bad news is not all are the same - if you've got to this point and your audio interface or mixer is expecting balanced signals - then look towards either ladik or happy nerding as they have some relatively inexpensive dual ones - you might want to look at the brand nw2s - they have some audio interfaces (including balanced ones) with a lot of i/o - other than that I don't think there's a whole lot of options - if it's not expecting balanced signals - then I would try to determine the source of the noise - it could be ground loops - there's a lot been written on that - in which case I believe it would be really useful to look at upgrading your audio interface/mixer to balanced i/o
"some of the best base-level info to remember can be found in Jim's sigfile" @Lugia
Utility modules are the dull polish that makes the shiny modules actually shine!!!
sound sources < sound modifiers < modulation sources < utilities