Many thanks for the input.
1) As far as wiring, it's already done: I ran four sets of new wires from the head unit back to the stock amps and simply tapped into the existing speakers from that location (bypassing the amps themselves, as noted above.)
2) As far as crossovers are concerned (passive or otherwise), I think I must be a little confused (not unusual!) I
thought some sort of crossover was
necessary in a multi-way speaker system to isolate the desired frequencies to be sent to each component. (Otherwise, wouldn't woofers, mids, as well as tweeters just receive--and attempt to retransmit--ALL parts of the sound spectrum with varying degrees of efficiency
)
I suspect my reasoning is faulty here, since the electrical schematics of the 420SEL's speaker system show no inline capacitors or inductors, but would enjoy being set straight by any of you willing and able to do so.
3) Finally, is there no objective measure to determine which speakers best replicate originally recorded material? For instance, let's say one were to set up sound measuring equipment at a recording site of say, a piano concert. Now, by means of various speaker layouts, crossovers, equalization, etc. in a given car's interior, couldn't one theoretically find the combination that best replicated the objective sound measurements taken at the original performance?
After all, it seems to me that injecting individuals' ears into the mix just adds subjectivity. You may like Infinities, the next guy MB Quarts, ad infinitum. But shouldn't the objective be to reproduce what the original performance/mix ACTUALLY sounded like? If the listener wants to tweak the original content to fit their personal tastes, then do so; but shouldn't the optimal speaker system's primary function be--by definition--to faithfully reproduce the original material?
Sorry for rambling on, but this inquiring mind REALLY wants to know!!!