I wouldn't recommend it personally. A "long-ish" time ago when I was a new extractor, I was making my changa out of DMT acetate, thinking it probably wasn't necessary to freebase based upon basically the same idea you have mentioned. The results were not very good. The dmt salts (acetates anyway, haven't tried other salt forms) seem like they don't want to vaporize correctly or in the same manner as FB thus resulting in hit and miss experiences. The vapor/smoke was quite a bit harsher as well, and this was with changa but I'd imagine that a sandwich technique or other techniques would produce similar results. Also, it seems like the stronger experiences from acetate would be in that "fast motion" craziness probably because the salts were burning...not sure on that though.
So, being a bong lover myself, I started making changa out of freebase and have never gone back. To me FB is the way to go, it just makes the most sense. Of course, take all of this with a grain of salt as this is just one man's opinion through personal experience.
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