Kenwood KAC-9105D (kac9105d) 1800W Class D Monoblock Amplifier
Yes of course it can be done however
i'm not sure if the stock unit has rca outputs, but you can buy a lineout converter which takes the speaker level connections and lets you connect them to an amplifier through rca cables.
Alternatively, you can get an amplifier that accepts speaker level inputs.
this is my amp, i think it does have the speaker level inputs, but i think i lost the little cable with the plug on it ;-( ive had this amp for like 3 years was like 1/2 price at best buy.
2016 Mustang GT 5.0 Magnetic Metallic Performance Package
Interior - Recaro Bucket Seats, Weathertech Digital Fit Floor Mats, Diode Dynamics LED Visor Mirror Lights, LED Glove Box Light, LED Trunk Light, and LED Map Light
Exterior -Dealer Installed Shelby GT350 Racing Stripes, SunTek Carbon 15% Tint, Diode Dynamics LED Switchback Blinkers, LED Reverse Light
Performance - MBRP Race Series 3" Catback