hello.. umm this post might not pertain to pioneer Hu's but i had a minor alternator whine too which my alpine 9855 used to pick up . now i knew it wasent my wires and i tried every possible re-route too.. but still the slight whine didnt go.. finally when i upgraded to MSD 8.5mm super conducting igniton wires... Bingo.. no more whine at all. They are superbly sheilded against the Electro-magnetic interference generated by the super strong magnets in our alternators.
so this post might not help pio owners but for anyone else who has the best wires and has tried everything to get rid of the alternator and still has the whine...Try the MSD wires. they are better for your car and so...it cant hurt .
thats about it
boom