What i am saying is that you should not worry about how much power is "being used" at lower volumes. There are too many factors that can contribute to how much power you are actually giving your speakers at a given volume setting. Even with a 150 watt amp, you might be giving your speakers less power depending on how much voltage your amps are operating at.

I could go on about this forever, but i'll try to make this short. Don't worry about how much power is going to your speakers at a given volume. Worry about what the amp is rated at (RMS power, not maximium power) and worry about what your speakers are rated at (RMS, not Max). That will be the safest way to achieve good results with your setup. Remember, underpowering speakers can be worse than overpowering them sometimes.

As far as tweaking is concerned, you can't really do anything with the stock headunit. You would need a crossover/EQ in order to really fine tune your setup. Otherwise, you won't achieve the desired center effect, especially with the stock placement of the speakers in our cars.

One analogy I could give you is that of a large car with a small engine. If a 4000lbs car has a 150 hp engine, it will not be a good performer. It will run, but not very well. Now if you give that car the power it needs, it will perform much better. Even if you don't floor it all the time, you will still feel an improvement. Now, if you give the car more power than it was designed to handle, it could get dangerous. Generally, speakers are similar in this regard.

 

You know, I trotted out that old saw about underpowering speakers last year, and I got bit-slapped for my trouble... so I'll share.

Most amps can't go more than 2X the amount of distorted, clipped watts that they can clean watts. That's a good upper limit to an amplifiers output curve.

So if you get a 75 wpc amp, it can go to 150 wpc if you clip the living snot out of it - which anyone could tell was sounding terrible.

But you're not going to blow your 150-watt speakers with that 75 watt amp. Even if you are sending the speaker a square wave, if it's within the Pe of the voice coil, it's within the Pe of the voice coil.

You MIGHT damage them with a signal that is inappropriate for their frequency performance - an excursion-related issue. But you will NOT blow them electrically.

 

If you go from 75 wpc to 150 wpc, the increase on a speaker is 3 dB - and 3dB is the SMALLEST volume increase that we humans can identify AS a volume increase. Anything less is perceived as a tonal shift.

So if you want to play a system louder, you might want to find other ways to do it besides bigger amps.

Doubling your cone are gives you 3dB more output too. Doubling your cone are and then paralleling the speakers drops the impedance, which can give you up to 2X the power and up to another 3dB.

 

Yea, you won't blow them, but might damage them. You're absolutely right. At least when you have too much power, you can play with the gains to make the setup less likely to blow. When you underpower speakers, you risk damaging your speakers at any given frequency blurp, which is pretty much impossible to avoid at that point.

 

I would like to also add that a simple changing of the placement of speakers can add a decent increase. Also, switching to more efficient speakers can help in this area as well.