Yes, its called an amplifier. I'd recommend you get an amplifier. 50Wx4 is good for a head unit, but going straight from head unit to speakers will give your really poor sound. Amplifiers take RCAs in, and it goes right out to the speakers. Get your self a nice sound card, a couple headphone jack to RCA converter thingies (should be about a buck a piece at radio shack) and just go right to the amp. This way you wont need a head unit at all.Is there such a device that will take digital coax and output it to 6 speakers (or even 5)?