http://www.marijuanagrowing.com/article.php?sid=23

Cannabinol, or CBN, is produced as THC oxidizes or degrades. Only a
trace of CBN exists in fresh bud. Stored and cured tops or hashish have
higher levels of CBN, that has converted from THC. Marijuana with high
levels of CBN generally make the toker feel disoriented and often sleepy
or groggy, often referred to as a stupefying high. At best CBN contains
only 10 percent of the psychoactive potency of the original THC.


I hope that clears some stuff up, the THC concentration IS NOT HIGHER in resin than in the stuff it came from, how could it be? the thc is burnt when smoking.....