I got this really good name but it has nothing to do with home entertainment systems. I want to profit from this site also via ads. I'm worried that since my domain name has nothing to do with the subject of the site it will be gimped from getting traffic. Any inputs?
Keep your good sitename (it's only a few dollars per year) until you make a blog or site on it. Also you can sell it. But for the home entertainment site, purchase another domain with some related keyword inside. For that, you can use the "domain search" of this site: http://www.domaintools.com
Spend some time developing it - if your domain isn't something that people would randomly type into an address bar, you're not going to make money from merely displaying ads. Like those domain landing pages, you mean?