I currently have an Infinity BassLink and at the time, I didn't know what I was doing, so it was the quickest and easiest way to get some bass. Now I'd like better quality bass. What combos would you guys recommend for good quality bass between $400 - $600? What options are there? I'm serious about getting something together, so consider that shipping will be costly, unless there's a local way to do it (I'm in Davis/Sacramento area, but willing to drive to the SF Bay Area).