How to mute audio effect rack if I didn't touch macro knobs?

[midiscripts]

Hi Ableton gurus,

I use audio effect racks on my return channels and trying to accomplish following behaviour:
- if I didn't touch macro knobs (all of them have 0 value) then the rack mutes incoming audio signal (return track does not produce any audio)
- if I've touched any of 8 macro knobs (at least one has non-0 value) then the rack unmutes incoming audio signal (and everything works as usual)

I tried to do it with Utility Mute button, but audio effect rack does not support mapping of multiple macro knobs to the same destination (mute button).
Please help.