I have tinnitus from too many years in the bike shop and going to concerts without hearing protection. I wear both plugs and muffs. Is it necessary? Probably not but I'm just trying to keep what hearing I have left.
I would recommend at least a 28db reduction.
Good earplugs will give you 30-32 dB of reduction when properly inserted, the thinner muffs are usually around 24-26dB, and thick muffs are similar to plugs.