I have a pretty bad case of tinnitus also. It acts up the most when I am stressed or don’t get enough sleep and also when I have been exposed to loud noises. There is a pretty big difference in ear muffs. Sometimes out at the range I do wear both muffs and plugs especially when I or someone else is shooting something really loud.
I have some Peltor ear muffs that are considerably more effective than the ones I picked up for a dollar or two at Harbor Freight. I would assume that the same variability goes for the electronic muffs. Price may not be the best indicator of effectiveness, so I too will be anxiously awaiting a response to your question.
Outdoors I wear one or the other, usually, because the sound disperses a bit better. Indoors, I always wear both, although I can never hear anyone talking to me. I went to an indoor range once and only wore muffs. I literally couldn’t sleep that night for the ringing in my ears. My buddy who went with me had the same issue. I believe it’s because the sound is more concentrated indoors.