Passive Subwoofers?

[xneox]

I've got a sort of unorthodox subwoofer setup. I wasn't running anything at all, and I had some equipment in the basement that I wasn't using.

-a 10" Infinity DVC (4ohm ea) car audio sub in an appropriate sealed enclosure.
-a Pioneer Pro-Logic receiver (VSX-505S - runs in stereo @ 150 wpc rms)

I rewired the sub for home duty - changed from parallel @ 2ohm mono to series @ 8ohm mono. I'm using the right bank on the receiver in stereo mode - 150 watts.

I get decent bass...better than not using a sub at all. Placement is nice, as it's small & tucked behind a cheval mirror that's in just the right corner...so it can't be seen.

I like using the receiver as the amp...it's there with all of my other components, and it has at least the same control over the bass as a standard powered subwoofer.

I do have two questions - the receiver spec bottoms at 6ohm. Is it advisable to ignore this & try running the sub using one channel per coil (4ohm each), knowing that I'll never max it out? Bass would still be mono, as the signal from my main AV receiver is a mono out, and would be split before the 505...so the coils wouldn't be fighting each other.

If not, is it worth my while to source passive home subwoofers? I'd really like to be using the receiver in its full capacity (both banks). But then, depending on what those cost, would the money be better spent on one high-quality conventional sub? Any input is appreciated. These are just random thoughts at this point...