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does anyone have any experience with Sennheiser's DSP360 Dolby Surround processor for headphones? I bought one with an HD535 headphone during the recent buy.com sale. I noted that when I began using the one I got, the volume control didn't work. I made the mistake of using the "Matrix" rooftop rescue scene as my test material and suffered temporary loss of hearing from all the whirring of the Gatling gun and the clattering of empty cases and the loud soundtrack. After about 20 minutes, the other switches (speaker/headphone/bypass) began working. Only then did the volume control work. Does anybody have anything similar to report?