The 2009 Boxster is slightly different than previous years.

The CDR30 non-navi has full-range balanced outputs, but they are very low voltage signals. I couldn't get above 1/2 V with a 0dB sine wave. This made me a bit concerned about using them due to potential noise floor issues. If it were my own car, I would have tried it, and if it were a hardtop, I would have tried it, but in a vert, I was less worried about it.

The car had Sound Package Plus - an amp and 7 speakers.

The HU has four preamp output channels to an amplifier which is under the passenger seat. The amp has 5 channels - L and R woofer, center, and L and right mid/tweeter.

The woofer channels are bandpassed, and the sub-bass is really limited.

The center channel is bandpassed and centered on about 1k.

But the last two channels - 4" mid/tweeter - are flat and full-range! No active crossover filter at all (the 4" mid has a series capacitor and so does the dash-mounted tweeter).

So we used the flat, full-range speaker-level amp outputs and ran those through a Zapco BTL attenuator into the balanced inputs of a DC360.4 amplifier (customer's). We ran 2 channels to the woofers (40-800 Hz, 24dB/octave) and the other two channels to the mids and tweeters (800 and up, 24 db/octave). The relative levels were fine.

Great sound, no engine noise (we did some tuning to decrease some of the OE speakers' breakup modes and to improve imaging... but no signal reversal).

So in the 3x3 Matrix I would classify this car as speaker-level, flat, full-range - with the possibility of using balanced signals and some kind of buffer amp/balanced line driver if I really wanted to eliminate any distortions from the Porsche amp (using OE speakers in a vert on this project, so it did not seem a big issue).