I auditioned the SC430 some time ago to see how Harman could help the poor Japanese. As you probably know, ML is a Harman company. It would be to go a little bit too far to say that there are actually ML stuff in the SC430 but lets say that the components are specified and tuned by ML but manufactured by one of Harmans many OEM factories that serve the automotive industry. Prior to the Toyota/Lexus affair with ML/Harman they turned to domestic brands like Pioneer and Nakamichi but appearantly they needed something that sounded better to the american ear.
If I remember my notes correctly the SC430 sound was not at all bad but had some drawbacks that I would find hard to live with in the long run.
The ML system does not provide a centre channel or any other kind of soundstage enhancement for the front channels. Instead they create a false spaciousness in the rear channels by adding reverb or delayed signals, not the same as extracting phase shifted signals like in a matrix decoder. This was probably done to derease the nearfield effect from the rear channels that are actually closer to the listener than the front channels. The result was however not that impressive, since they actually alter the original signal and try to create a fake acoustic environment you could get some very ugly side-effects with some program material. Not in my taste, anyway.
The overall spectral balance was good, still a bit to go to the effortless C70 sound, though. Especially in the bass the C70 has an advantage where it goes deeper and with less emphasis on the midbass. Focusing on the midbass is an old trick that is used to move the attention away from the deep bass which is much harder to reproduce accurately in a car. In the C70 you get real bass...
Midrange and treble doesn't really reach C70 levels even if it is quite good but I guess the Japs didn't have as much money to burn on speakers as we did
