If by DVD Extractor you are referring to DVD Audio Extractor from Computer Audio Solution (CAS) (the one I referred to above), then I believe it can read the 6 channel audio and downmix it to 2 channel. Have you tried that?
Many DVD Audios have both 2 channel and 6 channel hi rez tracks. If so, you can just extract the 2 channel files. In fact, looking at the Krell DVD-A, I think it has 2 channel tracks at 24 bit/96khz (according to CDUniverse) It may be that the 2 channel on that disc may be better than a 6 channel downmix.
Many DVD Audios have both 2 channel and 6 channel hi rez tracks. If so, you can just extract the 2 channel files. In fact, looking at the Krell DVD-A, I think it has 2 channel tracks at 24 bit/96khz (according to CDUniverse) It may be that the 2 channel on that disc may be better than a 6 channel downmix.