Ha ha cool. First off; do you have a YouTube? Please post videos.
Okay, use an efficient ported enclosure. Surround sounds don't have bass that's busting out like car audio. Your sub output on your receiver might be a little too high in frequency to sound good on a car sub; so if you use another crossover or your car amp or whatever to lower the crossover; you'll then have a gap in your sound spectrum; but the increase in bass you'll get if you use a good amp to power it will make up for this.
The built in amp for your sub channel is NOT enough power to amplify a 15 inch sub. Moreover, it might be meant for 6 ohms or more and your alpine 15 is certainly 4 or less. IF it is a dual voice coil speaker and you do try to amp it with your surround receiver, DO NOT connect both cause then it will be 2 ohms and will clip and create heat in your surround thing.
You can use ANY other full range amp to power it since it will already be filtered for frequency by the surround sub output channel.
