Here's another one I get asked frequently:
Q: Why do the same speakers sound "better" when the salesman switches to certain headunits or amps on the soundboard?
A: Have you ever heard the salesman say "this amp is better for bass" or "if you like brighter highs you need this particular headunit" or "this one is better for vocals" etc etc?
I have and used to wonder about it until we did some experimenting using numerous mid level/high end headunits/amps at one of my car audio meets some time ago. The major finding was that MANY headunits/amps had "built in processing"
even when the EQ was set on flat!
The headunits usually had certain frequencies
boosted or cut which
emphasized or de-emphasized a certain part of the music and some of the amps had similar processing going on (check out the review of the new Rockford amps in Car Audio and Electronics this month and you'll see what I'm talking about). Also, most people equate "increased output" with "increased SQ" so an amp/headunit adjusted to put out a bit more power could easily be perceived as "sounding better". I think it would be extremely difficult to keep all of the headunits and amps on a sound board the same in output/frequency response and even if they could I can't imagine it would be beneficial for the salesperson since then they couldn't say stuff like "this amp/headunit
sounds better than that one which is why it costs more" etc (as an electrical engineer friend of mine always says,
"if it measures the same it will sound the same".
) BTW, there were several other "variances" in the amps/headunits however one thing we noticed with the "higher end" units we tested was that the channels were more evenly matched and
most did not have "EQ curves" built in.
