The link that BayWayRic provided advertises 10% total harmonic distortion (THD), this is not an accurate representation of the architecture of the stereo system. I would be willing to bet this is assuming 10% total harmonic distortion (THD) when sound is being reproduced from a 2 channel source, to a 7.1 or 5.1 source. Obviously signal will be created from nothing, or even spliced away from something.
This is where the signal processing of the Lexicon technology outweighs Mark Levinson's. On the fly processing allows for minimal loss from original signals, while being able to truely reproduce the signal, especially in such closed quarters. In the eyes (and ears, lol) of an audio engineer) that makes it easy - closed quarters (e.g. a car). A home, a theatre, or studio, is entirely different.
Additionally, I was able to call a representative of mine who works for Harman International, who "off the record" informed me, while had no immediate white papers in front of him he was fairly certain the amplifier had been toned down, in terms of wattage, to provide as little distortion as possible.
It is also nice to note, the Mark Levinson system used in the current year model Lexus LS 460 is 19 speaker 450 watts 7.1 architecture. using the ML3-12 Amp. Notably similar to the Hyundai's amp, but with less power, older firmware, and different crossover topology
More here:
http://www.genesisowners.com/hyundai-genesis-forum/showthread.php?p=5995