amp gain question

well thats a touchy subject but heres my thoughts and more than likely some others an some maybe not.....

some think that they just blew the sub due to lack of power....but they have there gains maxed which is going to clip the signal which will distroy a speaker....so what I am trying to say is that if you back off on the gains on your amp then you should be just fine....rather if your amp was too small...and you wanted to compensate for it so you turn the gains all the way up....

thats my take on under powering

The input gain control on an amp will not limit the power it can produce.  An amp is designed to produce full rated power with the input gain control in any position.  So no, setting the gain lower will not limit its power output.  The gain control is designed to match the input sensitivity to the output voltage being supplied to it.  This is neceaasry in car audio because there is no industry standard voltage for line-level signals.  Have you ever seen an input gain on home amps?  No, because there is an industry standard for home equipment.

The gain control is used to match the amplifier's output curve to the source units input.  Set lower = higher voltage input.  NOW, if the input remains the same, then adjusting the input gain SEEMS to act like a volume control.  What you are doing is adjusting the amplifier to think the input voltage is something it is not.  The  common misconception is you have somehow limited (or boosted) the amps power output.  No, you have adjusted its performance curve at that one inpoint point to be something other than what it is supposed to be.  Set the gain too high and then when you turn up the head unit, the amp will clip.  Set it too low and you lose the ability to listen at low volume levels.  But the amp will still produce 100% of its rated output.

Oh, and I've said it before and I'll probably say it a hundred times more: underpower CANNOT harm a loudspeaker if the amp is set up properly.  OVERpower and clipping harms loudspeakers.  It's called physics.

Now, if you install a nice big SPL system and your bass is too much to use on a daily basis, the only thing you can do is change your system, lower the overall volume, or cut the bass using an EQ or the tone controls in your head (or some other processing device.)  This is a common result with people who install big amps and big subs: it sounds like a cool thing to do and it looks great, but you can't really listen to it.  Indeed, most people who compete seriously would never use their 150db competition car for daily driving and daily listening.  They'd go deaf.  One trick I've seen is to cut the signal going to all but one driver in a multiple sub system for normal listening and only "turn on" the rest of the system for competition or showing off.  I also know people with multiple amp setups: a conservative 100 or 200 watt amp for daily listening and a 1500 watt monster for competition.  They switch the big fella on maybe once or twice a month.

Dyohn can you input on your thoughts of underpowering a sub