Your alpine amp looks like the lowest supported impedance is 2 Ohms for the subwoofer channel. Run anything lower and you'll likely find the amp will shut down. My suggestion is to get the D4 (dual 4-ohm) version and wire the voice coils in parallel (producing a 2 ohm load). You'll get the most out of that amp in this configuration, and I think that is the most popular version and hence usually the cheapest version of that sub.
The amps that I have seen that have been 1 Ohm stable tend to be switching class D amps intended solely for subwoofer use. They are extremely efficient (compared to thier traditional counterparts), but like anything they have a tradeoff: higher distortion. But for a subwoofer channel the added distortion is generally undetectable.
