Hi. i was wondering if anyone on here would be able to explain to me how to install a 4 channel amp and a mono amp as well. i attempted it,,but i wasnt getting hardly any pwer to my subs. so i currently just have my head unit installed with my mono amp. i have to use my hu rear pre outs for my subs to work right. my head unit has a pre out for "woofer" but its only 1 rca,and my amp takes 2. i did try the y splitter for that,,but still was barely powering my subs. Can i run rca cables from 1 amp to the other? im pretty lost on this,,lol...any help is greatly appreciated! ive been on this for days now. ps...my hu has a set of rca's for fronts..a set for rears...and a single rca(All female) for "woofer" i would think i should be able to do this.

Do you have your sensitivity all the way up on your sub amp?

The 4CH amp can be hooked up to the front or rear pre outs on the HU. The mono CH amp gets hooked up to the SUB out pre out on the HU. Im sure you already know that though. You mentioned the word "subs" so I am guessing you are running a subwoofer box with more then one subwoofer right? If so then you are trying to power two subs from a single channel amp and the end result will be an amp that is only going to give each speaker half of the amp rated power. A single channel amp should only power one speaker.

Are you running the correct ohm speakers? Post up what equipment you are running so we all know exactly what is being used here. I run the exact setup in my car except I run a 2ch amp to a pair of Polk components. I do not run rear speakers.

Thank you for the reply by the way. im running an SSL evolution 3000 watt class D monoblock amp. To power 2 JBL GT SERIES 12" 275W RMS COMPONENT SINGLE VOICE COIL subs.i wired the subs in parralel.and have them in a sub box. They actually hit decently...But as i said,,only if i connect it to HU rear rca's. And my 4 channel im attempting to run is also an SSL evolution 1600 watt amp. I was trying to hook it up to my front and rear speakers.(4x6 & 6x9's)......I hooked my 4 channel up to my front and rear outputs on HU..and it worked fine...But when i used my sub pre out for my mono amp..my subs would barely play. So i got frustrated and just took my 4 channel back out. IT sucks cause i just paid for it,,and would like to use it...lol. thanks again

And i called tech support for my HU. and unfortunatly there is not a subwoofer control feature. They suggested the y adapter,,but i already tried that.HU is...Boss BV9982I 7” Car Stereo DVD/USB/SD/iPhone Player

How familiar are you with that HU? Do you know all the controls on it? I ask because I know some HU have a boat load of different configurations and sometimes the wrong setup can cause the volume output to be quite low. Have you ruled out each component yet by trying the subs in another car? Do you have a local audio store around you that would hook up your amp and subs and play them for you to rule out any issues with them? This could be helpful in ruling out certain components.

I think i have it figured out. I had it connected correctly all along.Im not sure what was causing my problem originally. the only difference is i had the car running this time when it worked?? anyways..i noticed above you said something about me only getting half the power out of my amp because im running 2 subs? as opposed to just one sub? Thats interesting because i didnt know that.

Mono amps are used because of 1 signal, not because you can only run 1 speaker from it... Most mono amps are rated at a certain power @ 4 ohms. But if you add speakers and play with ohm loads, you can get more power from it, the lower the ohm load gets (on certain amps, not all created equal).

You need to ensure that all the stuff on the amp and HU are turned off. My amp and my HU have crossovers, but it's better in the HU, so I turned it off on the amp...
Check all the settings in the HU menus....

Adding a speaker doesn't necessarily half the power... on most amps, if ran parallel, it doubles the power, plus the whole other speaker playing, it's louder for sure.

Rafael