DC spike remove ???

Hi, I just started experimenting with rtl-fm with a DVB-T stick and a raspberry pi 2. It's really very simple to use but I currently have a problem by setting a frequency in NBFM mode. When I slightly shifts the frequency of the true frequency , it appears intermodulation with DC spike even with the dc -E parameters and offset -E ??? The problem does not exist with automatic gain. IQ balance dont work with a fixed gain (ex -g 30) or i made mistake in my command line ??? Have you ever encountered this problem? Thanks, Arnaud F6GNJ