I called Alpine tech support yesterday, and had emailed them over the weekend. Not surprisingly, I received 2 contradictory answers re: setting the gain. One tech said, yes, gain must be adjusted when installing new speakers. The other said, no. He explained that gain settings on an amp and subwoofer apply to the signal going to the head unit, and if you're not changing the head unit you do NOT change the gain settings when you replace speakers. He insisted that anything downstream of the head unit (e.g., speakers) is not affected by the gain settings.Yes, you should definitely tune the amp and radio to adjust for the new speakers. Usually everything is set up to handle the stock sound, so you should always adjust when you add anything,
Thanks Alpine. So who's right?