i promised i'd post a response once i figured out what was going on. i'm fairly sure i know where the cause of the crackling lies.
first, some have speculated that i have noise in or around my system. there are no fluorescent lights nearby (at least that are on), and i have two dedicated lines from my breaker box to a quad receptacle to power my hi fi equipment. so i don't think that is the problem. also, i tried the suggestion from almarg, and set my tuner to an am station but did not hear any crackling through the tuner.
i think the problem is in the phono stage itself. the only way i can get the crackling to stop is by tapping on the back of the gcph. the crackling stops completely. note that i have made sure all the connections in and out of the gcph are secure. i'm using balanced connections out, the grounds from my TT are very tightly secured, as are the rca's from the TT. again, a couple taps towards the back of the phono stage and all crackling is gone, at least for awhile. i figure there is something loose in the phono stage.
if you have any other thoughts let me know and thanks again for all the suggestions.