I was remembering N130gv2's post and he has a great point. You have already verified the subs work well ("they banged hard" with a friends amp) so this isnt a mechanical or box issue it is an electrical setup issue

Your amps ratings are:
110W x 4 Max Power into 4 Ohms
150W x 2 (at 2 Ohms) + 300W x1 (at 4 Ohms) Max Power
60W x 2 RMS into 4 Ohms
65W x 4 RMS into 2 Ohms

so what is your woofer impedance and how do you have it wired? It is a 60 watt amp you dont use MAX power for amp ratings you use RMS ratings... it IS a $70 US dollar amplifier... AND IT IS A 4 CHANNEL OR 3 CHANNEL AMP NOT A 1 OR 2 CHANNEL... wrong amp for the job

 

id say ignore all the headaches with this amp, throw it in the nearest trash receptacle and go buy a real sub amp, even if you wanna go with sony they still make mono or two channel amps, the end

 

What subwoofer do you have? It can only be two possibilities
a) As the above poster mentioned, reversed polarity on the install
b) Depending on your subs, 60 watts is probably no where near enough.

The remote wire just sends amps a signal to turn on, if the amps turn on, remote wire is fine.

 

I'm going to agree with the majority here. Buying a new amp is the best solution. If that's not an option, channel 3 and channel 4 need to be "bridged". That means one positive from ch3 and one negative from ch4, and the white and red RCA's connected to ch3 and ch4 (orientation is up to you). Your positive and negative leads will need to be wired to the sub to achieve a 4 ohm rating (hence why "what sub do you have" was asked). This setup will give you 300WRMS to both subs. They will need to be wired together and in phase with each other. If you provide what type of subwoofers you own, or at least the ohm ratings, myself or anyone else can describe the proper way to wire your current setup.

 

My bet is that 1 sub is "mismarked" on the polarity.
Take a 9 volt battery and for a split second connect it to the speaker terminals. (the positive of a 9 volt is the smaller one)
When the polarity is properly hooked up, the cone should move outward / away from the magnet.

Don't connect the 9 volt to the subs for more than a split second as it could overheat the voice coil. Don't try this trick on a small midrange or tweeter.

 

Just provide what subwoofers you have and we can go from there. Once we know what we're trying to work with, we can give you some solid solutions instead of "try this" or "try that".