I haven't yet done that, but it is an excellent idea and I will certainly do it as soon as possible. I suspect it is a phase issue, because when I looked at the waveform of the LFE channel, after decoding to six mono files, it appeared to be the same as the source. I have my receiver set for a crossover of 80 hz, so that everything below that in the main channels is diverted to the subwoofer. This filtered bass may be partially cancelling itself out when combined with the LFE channel in these instances. In addition to just playing the subwoofer without the main speakers, I'm also going to switch the settings so that the mains play full range and the subwoofer only plays the LFE channel and see what happens then. It's possible that it could be a quirk of the speaker distance settings in the receiver, and that the results would be different in another room and with different equipment.