Gains are there for that purpose. You could connect a 1,000,000 watt amp up to a 100 watt speaker and as long as you set the gains correctly it wouldn't blow it. Your HU, even if it CAN output a full 4V through the pre-outs, wouldn't output that much voltage unless the volume was turned all the way up. It doesn't output 4V all the time. That's why it's suggested to set gains with the volume at about 3/4 of the way up. That way you can always turn it down for music that has a higher than normal recording level and turn it up a little more for the music that has a below average recording level. The one thing you've not mentioned that I would love to hear about is what you think of the DCON's.