*Siento

But the problem there is that it induces another variable to the buyer: What amplifier sounds good? What amplifier sounds bad? When, in fact, the decision is extremely controversial.

Fact is: Not all amplifiers sound the same
So I'm not too surprised if the Crunch amplifier may sound better. After all, it might have a better low-end response wherein it boosts certain low end frequencies (Rockford used to do this and their customers loved it). But what if the inherent vehicle acoustics has a boomy low-end where 100hz has a huge peak? Then the Soundstream's "thin and clinical" would give a better balance than using the Crunch that would have exaggerated this peak further.

It's a very much case-to-case basis and there are a lot more variables affecting the sound. In order, they're probably:
1. Vehicle Acoustics
2. Speaker Positioning
3. Tuning (EQ, Crossovers, Phasing)

Then there's the fourth criteria: speaker sound signature. After that are minor variables coming from amplifier sound, cable impedance differences, etc. Then again, this is pretty much my opinion on it.