Amp and Sub with standard speakers?

[Greenman]

Hi all.

Has anyone just upgraded to a side sub box and sub, with a monoblock amp to run it, and kept the standard speakers and HU?

I have an RSN510, but some of my side speakers have stopped working and i'm going to take the car down to a local car electrics place to see if we can work out whats wrong.  I might get a sub and amp fitted at the same time, but if they cant be fixed i might go 4 channel amp and some front components.

[Beej]

I will be running a sub over the next couple of months keeping the factory headunit, planning on disconnecting the rear door mid/bass speakers and running them to a line out converter and running a gain control to allow for a little volume adjustment. I will changing out the mfd2 for either an rns 510 or kenwood dnx and speakers also at some point, but for now, just looking to help what's there a tad!