depends if ur only preout is a sub out... coz then the deck will only be sending sub frequencys so it would not be suitable to run speakers off of

No my headunit is not a sub pre-out but i am using a 4-channel amp. So far i have only bridged 2 of those channels to run my sub which is on a LPF.

Well there shouldnt in most cases be a sub out RCA output channel without there at least being a seperate "front" channel

What ED911 has done is fine ad will work a treat...espescially helpful for those who only have the single RCA out (Pre-Out) connections on their head unit.

As far as signals .... it wont matter T-Piecing/ RCA Y-Splitting the signal cable from speaker to sub amps.....when these days almost all new amps will have the signal filters....so signal comes from HU to sub amp....have LPF turned on...no highs will come ut the subs and then the reverse for the split speaker amplifer where either BPF or HPF will be on.

What you will have lost is ability to Fade channels unless you have a fader on the amp itself..that can be manually setup.

Because at the moment you have all your speaker placements/sound stages etc all off the one signal from the head unit....thus u can calibrate it....so balancing left to right will still work but not front to back...in your case ED911 some fading will work as some speakers you are still running from the headunit.....

Doing it this way will also retain your pre-out voltage value. As splitters divide the signal up in parrallel not series so you wont get a voltage difference (unless its split like a dozen times ) such as in daisy chain setups but even then this can be countered by increasing the gains to suit.

What will also be effected is sub control from the head unit....you will have it from the mono/sub amp....but adjusting subwoofer settings from the hu you will find either wont work or will effect the signals being passed to all amps off that line....This is why it is important when costing an audio system that the head unit should always be looked at as being the most important(thus dont skimp on it) component..not subs or amps..

um i know its not relavant to a person without this feature, but i would like to mention, great amps have the rca output, meaning you can put another amp by using another set of rca's to go from ur current amp to your new amp, no need for spliting.

Yeh i regretted to mention this point due to his amps not featuring this ability. A note to daisy chaining amps tho...there not designed for linking say a monblock to a 4channel ... its more for amps used for the same purpose..say linking 4x sub amps to all hang off the sub channel pre-out from the headunit. Its normally available on monoblock amplifiers compared to other amps