That's quite a high dose of clonazepam (I haven't taken more than 1.5mg/day), so keep in mind that it will induce some respiratory depression (slow your breathing down), and 250mg of DXM is enough to metabolize in to a big enough amount of DXO [dextrorphan] through CYP2D6 O-Desmethylation, which is DXM's active dissociatve metabolite for which DXM acts as a prodrug for, which should get you feeling moderately dissociated, since it's close mittto the usual dose of 300mg DXM, usually dosed without benzos.
Also, the DXO metabolite causes respiratory depression in dissociative dosages, which will only be amplified by benzos, opiates, alcohol, tranquilizers, but on the other hand, benzos keep your lower your HR/BP caused by the DXM parent drug. So, I would recommend dosing DXM and other "dirty" (in terms of Neurotransmitter receptor selectivity), seizure-inducing drugs that act on the norepinephrine and serotonin receptors with low doses of benzos, such as 0.5mg of clonazepam, or 10mg of diazepam, 7.5mg of temazepam, or 1mg of lorazepam, especially if you have heart problems. These benzos are best for DXM-induced hypertension and tachycardia due to their physical, muscle relaxant, and anticonvulsant, but a larger dose of Xanax (1mg) may suffice if the other benzos can't be found. If you have an extreme benzo tolerance (not something you want), double the dosages I mentioned if you are exploring high-plateau stages of DXO dissocation.
