I am not looking to break the bank but I was going through some of my stuff and I came across a amp I had forgotten about it is a boss Audio rev 135 75x4. I also have a infinity kappa amp and 12 inch reference setup that needs to be installed I am looking at switching to a after market system would the boss audio amp work with some infinity reference 6x9s that i have been looking at. I am not looking for all out bass just a nice thump I am looking at a pioneer headunit. will I have any troubles getting them all to work together and sound good

assuming both amps have RCA inputs, and the HU you pick has front, rear, and sub RCA outputs you should have no problems.

I hope you dont plan to run the stock speakers at 75 watts each.

no I would run the infinitys on the amp

Sounds like everything will work out. The only thing I stress upon is setting your amps gain properly so you dont blow anything up.

To do that, once everything is hooked up, turn the amps gain all the way down/off. Go to your Head Unit and turn the volume up about 3/4 the way. Go back to the amp gain and turn it up until you hear distortion, then back it down until the distortion is gone.

You have just set your gain/* properly. Having another person to help you out is better than doing it on your own, but it can be done by yourself too, you just have to have a good ear.