Thanks for the suggestions Doxquzme. The sony is appealing, half the price of the Alpine.
The Alpine power says: 50W x 6 @ 4Ω + 150W x 2 @ 4Ω or 50W x 6 @ 2Ω + 300W x 2 @ 2Ω (4Ω, 14.4V, 1kHz, 10% THD).
My speakers are 4ohm. The factory tweeters are 2ohm 20W (the front at least to my...