Our drummer, also a pro sound guy, OUR sound guy when he plays with us HATES my effects running through his IEMs .... so my first fix was to stop using them, then he didn't like the Spector Bass (Q5 w passive pups/active tone) when I messed with the tones. Fixed the tone issue by keeping them flat at 0/0 gain/loss. I agree they are a little weird. He loves the active Precision bass (shocking typical sound guy response). The two effects pedals I've alternated are an old (really old) EHX Chorus/phase shifter and a newer Digitech RP80 also while using the phase shifter..... My current solution is to split out the "clean" signal and send that to him, using two GKMB115s stacked, one clean, one with effects. Thoughts? new pedals or new sound guy?
Tell him you don't like the sound of his drumsticks and never have, but you've kept it to yourself... Totally confuses them!
Hard to say as we can't hear your sound; maybe he's right, maybe not? Can you get a second opinion from someone else you can trust? Also, is it only a problem with the IEMs or does he dislike your sound in general? Most import is good FOH sound, what you hear in the monitors is IMO primarily for hearing what everyone is doing. Nice if the sound is great there too, but you may have to compromise a bit.
+1 What he gets in his IEM could be totally different than what you send to FOH. Definitely the easiest solution. As far as bass tone, that's a personal thing just like his drum kit. How would he feel if you ragged on him about his snare, cymbals, etc.? Live and let live-if you have someone so worried about your tone (unless he's paying you) it strikes me he's not keeping his own yard clean. My personal favorite drummers just smile and groove and play great and are generally cool people. The control freaks I've run into seem to only get so far in the Biz.
I've played with one or two guys who drove me nuts with their heavy handed chorus or flanger. They thought it sounded great and had it on most of the time. I thought it sounded like crap. Take a poll, listen to some live recordings,