Quick and dirty

Info

Disables effectors
Effectors init order should be distortion->chorus->flanger->gargle->(loops)

Warning

Should work quite reliably for any version of IIDX27-31
Leaving out IIDX25-26 until I make sure patch doesn't cause video playback to break

In hex editor search for these patterns and patch first 5 bytes of pattern to NOP (0x90)

distortion: E8 4A A2 00 00 90
chorus: E8 9A 99 00 00 90
flanger: E8 CA 89 00 00 90
gargle: E8 AA 82 00 00 90

How to identify

Missing necessary documentation