speaker impedance varies over the frequency spectrum and can peak high and low
depending on the music and power fed to it can be a problem especially at the low.
the impedance is "nominal" not average, not median. a 4R speaker can drop down
to where sustained amp usage is not recommended (by the manufacturer - do check
their manual).
you do not have to worry unless the speaker is a 4R (nominal) (with lows that suck power)
and you PUMP UP the volume. best case, low-to-medium volume is OK.
worst case, low bass heavy, super trebles, tone controls maxed out, with heavy/death
metal intended to rattle fillings, your windows, your neighbor's windows, signal aliens,
and you turn it up even more.
one transient or some component (active, passive, in the signal path, out of the signal
path, input from your source, etc) failing then that takes out one driver then the output, then
the rest fails due to cascading or exceeding limits, then the rails short the entire paralleled
output stage and sends 40 to 80 volts to your speakers, then bass pops out of
basket, the treble coils melt, then the amp fuses or protection kicks in after the fact.
love rock but if loud is your thing, rethink these poor speakers that usually destined
for background news, classical music, elevator versions of 70's Rolling Stones.
think quad CV D9s or quad L100s, backed by 1000wpc amps.
but before you get nervous, download the schematic for the amp, and look at the
protection circuit. if it's just a simple (marketing speak for cheap) fuse, then find some
super fast fuses. find the lower of the maximum power of both speaker and the amp.
then using nominal resistance, calculate the current at this lower maximum power,
then consider derating the fuse. then buy them by the bag no matter how expensive
it is - your speakers AND amp are far more important than saving a couple of pennies.
My Hafler 101 had an added headamp that blew the 1/16A (as I recall), and it was
a hassle to remove to replace the fuse in my rack. This and the replacement 1/10A
fuse was somewhere between $5-10.
Crossover cap values are pretty critical to frequency response.
