The problem is that regardless of whether you're taking in RIMAs or not, the SSRI itself will make smoking DMT largely a pointless endevor, unless you feel like radically upping your dosage.
SSRIs increase the amount of free 5-HT floating around the brain, which means that a greater percentage of the 5-HT2A receptors (which are the receptors that DMT and other psychedelics act on) are likely to be already bonded to a 5-HT molecule, so fewer DMT molecules can exert an effect. Consequently, it takes much higher doses for any psychedelic to be active if you're on an SSRI.
I had a friend on Luvox who wanted to trip with me. I ate 2g of P. Cubensis and had a vivid, visionary experience. He felt absolutely nothing, even after five or six really heavy bong rips (which really bring out mushrooms).
That said, SSRIs and RIMAs probably shouldn't be mixed, esp. since you already need a way higher dose of changa than your ordinarily would.
Blessings
~ND
PS: if I got the pharmacology of SSRIs and psychedelics wrong, anyone can feel free to correct me.
"There are many paths up the same mountain."