My first reaction would be "it matters to a point", followed by "no you can't". However, if you have low end subs then the HU really isn't going to make much of a difference amd depending on your setup one HU might sound the same as another to you while having very different sound qualities. For most low to mid-range subs the amp is going to be marginally more important than the HU. What are you running (or looking to run) in terms of subs amp and HU?