An update on the Odyssey monos. I spoke with Klaus today, who suggested perhaps the amp's brightness was a result of them being out of bias. Over the telephone, I worked with Klaus' associate, Michael, and tested the bias of the Left Channel amp using a multimeter. It was, in fact, out of adjustment, so I re-biased the left amp with Michael walking me through the process. He suggested I listen tonight, which I did. The adjustment made a significant improvement by sweetening the upper mids and highs, and thereby removing the hardness and glare. The Mono Extremes now have a nice balance from top to bottom.
Tomorrow, I intend to call Klaus to thank him, and have Michael walk me through checking the Right Channel amp. Might as well get them back to spec to hear what they're designed to do.
Kudos to Klaus for encouraging me to call him.