Ok here's Swim's take on it:
Pure n,n-DMT, those nice fluffy white xtals that you get from a naptha freeze, are pretty but they aren't where it's at. These have what Swim likes to think of as a very high frequency "buzz," which he considers to be the "ultraviolet" end of the plant spirit's spectrum. Jungle spice on the other hand has a low frequency buzz, and is the "bass" to n,n's "treble," if you will. This seems to be the component responsible for entity contact.
In Swim's analysis it's as if the low frequency vibe of the jungle spice, rather than projecting you out into hyperspace, brings the hyperspace to you. When smoked by itself, you generally don't go anywhere, but there are entities a-plenty right there in front of you. Smoke 'em together for the "full spectrum" experience.
Yes, set and setting are major factors as well. This is spiritual stuff folks, if you don't believe in spirit that's fine but that's probly cuz you haven't really looked. Start messing around with ritual/ceremonial magick, saying prayers, doing blessings, having sacred stuff around, making pilgrimages to sacred places, smoking during special times like eclipses, equinoxes, etc. This WILL make a difference. Apply the methods of scientific inquiry to this. Don't just say to yourself "There's no such thing as spirit, it's all in your head" when you don't really know that. That's not being scientific. Science means trying something and seeing what happens. You don't need to believe, in fact blind faith is the opposite of what you need. Just keep an open mind and be willing to "suspend disbelief" long enough to see what happens.
On a related note, swim has noticed the "breakthru denied" phenomenon also due to certain spiritual reasons, such as smoking for the wrong reason or at the wrong time. Same batch that had been a powerful reality-shattering bomb on other occasions, doing absolutely nothing when used "improperly."
Getting back on topic, doing toluene pulls will give you the full spectrum alkaloid profile, which Swim and his friends have given to enough people that had smoked the white stuff before, and inevitably they all agreed that it was in a totally different category, WAY more powerful than just those fluffy xtals that look good but don't do a tenth of what the plant is capable of doing.
But forget toluene. Swim now uses only d-limonene to extract the spice. This gives a COMPLETELY different feel, more fluid, and it lacks that certain dark tinge that every petrochemical experience he's ever had has contained. It's hard to describe but try it yourself and you'll see what Swim means. It's more natural, friendly, loving, and magickal... less "dark and scary." Puts you more in touch with the energy web that connects all things.
The Ultimate Secret of the Universe is that there is no Ultimate Secret of the Universe... there's just a bunch of stuff that happens.