Well I started the topic with no real direction to it. If someone wants to talk technical then we'll talk technical. Some of these things are precisely how you can tell a sub is good or not without even hearing it.

Good, big, small, better? All relative to your expectations. Not everyone has the same goals.

Unferth, did you mean wired in series? The Tumult is a dual 2 ohm sub. Or did you have some special version made? If you have it in parallel then you're running it at 1 ohm. The amp may be going into a protect mode which may be confused with clipping, even with the indicator light.