I tried mixing & matching standard cans with TORs, just to play with the noise. This was back in the days before Tuneboy. Tried 1 standard, 2 TORs and also 2 standard, 1 TOR.
Didn't seem to make any difference to my tune or performance. I just did the 12 minute tune afterwards, and all was well.
The sound obviously mutes with each standard fitted, but that seemed to be the only effect.
This was all with the catbox bypassed. Do the French insist on that being on as well?