Here goes my tirade.
I have a Panasonic CQ9800U head unit. It's connected to Rockford Fosgates
T1693 6x9 coax on rear deck and P152S components in front with separated
tweeters. Problem now is that when i turn the volume little above half way
up (around 25) on bas, the head unit's amp shuts down. Unit is constantly
working, but it's like the head unit's internal protections kicks in. At
first we thought it might be the power cables, but when we drove cables
directly to car's acumulator and a separate ground cable, it continued
still. Head unit is rated on 4x70W max (i think it's around 4x23W RMS, or
something like that, i don't have manual with me now). Comp speakers in
front are 60W RMS, and ones in back are 110W RMS. I don't have an external
amp, so i know that's one small problem, but, at time, i didn't have money
for it, i thought of buying it later.
Problem now is why is my head unit shutting down. I constantly get dealers
saying "oh, your speakers are too powerfull", but that's got nothing to do
with head unit's internal protection kicking in on bas. I mean, if the
protection is kicking in, obviously, too much current is coming in it (since
we established that power cables are okay). Now, too much current can be
coming from 2 sources. Either some of the speakers are faulty, or the head
unit can't give out as much as it is saying it can. I mean, i never expected
it to give out 70W, not even 20W, but, as much as it could give out (even if
10W) it's internal protection shouldn't kick in at any time. As i understand
it, if i'd hook a 1000W/4 ohm sub to my head unit (properly working) and
turned the volume up, it wouldn't shut down, but there would also be no
sound, because head unit's amp isn't powerfull enough to drive a sub. Same
thing would be here, if the speakers are "too powerfull" for the head unit,
head unit wouldn't be able to drive them to their full potential, not the
other way around.

What i've tested so far is:

Ran separate power/ground cables.
Put the head unit out of the dash on horizontal position and tested
(protection kicks in).
Tested it while car's motor was running and while it was not. Same thing,
protection kicks in.
Tested just on front speakers. Same thing, protection kicks in.
Tested just on back speakers. Same thing, protection kicks in.
Tested another CQ9800U on same setup. Protection kicked in on that one
aswell.
Tested on some other alpine head unit. Protection didn't kick in. (this one
was rated to 4x50W), but about this one, dealer said that it didn't have
internal protection so it left me a bit confused as i couldn't take it as a
sure thing then.
Tested on songs with lower bas, protection kicked in, but later on the
scale.

Now all i have to do is put my old panasonic in there that i drove 3 years
almost all the way up the notch, that never shut down on me, in this same
setup and see what happens.

Can anyone give me suggestion what else to try/test/ask/research/anything
Or if maybe someone knows why/what is happening here because a reason "your
speakers are too powerfull buy an amp" isn't satisfying since speaker power
has nothing to do with it from waht i know. Buying an amp is obviously the
solution, but first i have to be sure head unit isn't working properly, so
the 100$ i spent on extra head unit power, i'll spend on an external amp and
demand a lower price model head unit.