Thanks for your input, makes sense.it 'should' do with the way the amps are designed.
i am by no means a expert on any of this(just a guy with a internet connection )
from the statements made by both amps--from either their spec sheet, or the online store, i am lead to believe that the Sure series of amps are designed for small projects where the amps would stay permanently installed, in a non-mobile environment.
comparing both the 4x100, and the amp9, there are visible power filtering devices on the amp 9, that are not present on the Sure 4x100:
the amp9 has some large storage capacitors--these both provide a level of incoming power filtering, and some reserve power for the amp chipset(only a little as capacitors can discharge their entire storage capacity very fast, but if the draw is small, it can take a while to discharge..).
the amp9 also has some visible coils-- these are mostly low-freq power filters but power filtering none-the-less..
the Sure 4x100 has some visible coils near the input stages, but no visible storage capacitors like other amp designs..
after briefly looking at other amps in the Sure series, there are some very small supply capacitors on many of the designs, but nothing like any other amp design i have seen-- most amp designs will have larger capacitors similar to the amp9-- because it allows for more power-- both for filtering, and for storage..
so after my non-expert look at both designs, i would have to say that all the sure-series amps will require voltage, and power regulation in a car environment, because none of them appear to have sufficient filtering built in..
this is probably the biggest reason that they are so much cheaper then the amp 9, or other similar tripath-based amps that cost more..