ok i finally bought a multimeter today to set my gains properly on my JL amps... i noticed that i had my gains a lil higher than what JL recommends... but the weird thing is, all this time i thought it sounded nice, and i coudlnt hear no distortion at all...

when i bought my multimeter, i adjusted all my amps to the specs JL recommends, is it true that when a speaker/amp goes into clipping, you sometimes won't be able to tell with your ears? I didn't want to ruin my speakers by pushing them too hard into clipping so that is the reason why i bought a multimeter to set the gains...

for example, i have an alpine headunit, maximum volume is 35, so i set my volume at 75% which is 26, and set my gains properly... now lets say i listen to my music from now on and once in awhile would like to set the volume a bit higher, perhaps 28 or 29, would that hurt my speakers? or amp? please let me know... cause some music are low and others are really high, its weird... its like each music is recorded at different levels, so really even if you did set your gains properly, certain songs can go into clipping if they record it too high, am i right?

and alpine's bass setting is 0-15... its weird, 0 is actually -15 and 15 is actually 0...

i usually keep it on 8 anyhows, cuz 11 is 75% for the subwoofer level...

i set my sub gain with a 50hz mono tone, and the components and rear speakers with a 1kHz tone...

 

IMHO, it's overkill to try and set gains electrically, but learning the limits is a very informative exercise if you have the ability to do it. The lower the gain is, the lower the noise floor, so I tend to like to keep them as low as I can while retaining the ability to get as loud as I like. As you noted, you're never listening to a pure 50hz sine wave, and all music is not recorded at the same level. Even if you normalized all your audio, you'd still find vast differences in perceived loudness due to differences in dynamic range.

Depending on where your subs are you may or may not be able to hear them distort. If they're in your trunk with the seat back up, it acts like a natural low pass filter and you may not be able to hear it. Its also very easy to confuse distortion for rattles. I suggest finding a variety of hard hitting music, turn it up and get back there and listen to them carefully (that does NOT mean put your ears up to them... LOL). You might temporarily disconnect the highs so you can just hear the subs play. Once you get an idea of the limit you can keep it to a safe volume by "feel".