I tested both ways. With OSA, without OSA.
OPrivacy works with no problems whatsoever. You don't need "OSA for Ostim" to run it.
Naughty Voices 2.6 is another story. It didn't work. I tested with OPrivacy installed, I tested without it, and I tested with OSA for Ostim... the characters were still silent. I only had the necessary mods to run Ostim Standalone, I didn't have anything else to avoid any possible conflict.
People can try it for themselves, but there have been conflicting reports if NV 2.6 works for Standalone or not. 2.7 is the one built for Standalone.
( Just in case, make sure that NV is lower priority than Ostim SA since ostim sa has their own sounds so Ostim > NV so that NV overwrites it )
That's odd, I'm running 692 mods with 609 active esm/esp/esl, I'm not sure if I can say that mine is running properly since my first try was with NV 2.6 with ostim standalone and I've never used it before but npc's comment during sex. (excluding custom voiced)
Just to give a better perspective, they let me know if it feels good, if they want it faster, when they are about to orgasm and when I orgasm among other idle chatter during sex along with a sentence after we finish ( Thanks that felt great ) or something like that. Is it correct to assume that it's functioning or? If not I apologize for getting your hopes up, I was just trying to help >.<