A:Answer It depends on if the subs are 2 ohm or 4 ohm and if they are wired in series or parallel. For speakers wired in series, the total impedance is the sum of the individual speaker impedances. For example, for two 2 ohm subs wired in series, the total impedance is 2 ohms + 2 ohms = 4 ohms. If the same two subs are wired in parallel, the total impedance is the square root of the sum of the square of the individual impedances. Since the individual impedances are the same, the total impedance is simply half the impedance of the individual sub. In this case since the individual sub impedances is 2 ohms, the total impedance is 1 ohm.
Now regarding the Alpine amp, it is stable at 2 ohms. Your speaker system impedance can be equal to or greater than 2 ohms but not less than 2 ohms.
If the two individual subs are 2 ohms each, the Alpine amp can drive them if they are wired in SERIES since the total impedance would be 4 ohms but NOT wired in parallel since the total impedance would be 1 ohm.
However, if the individual sub impedance is 4 ohms, the Alpine amp should be able to drive them in series or parallel. The total impedance in series would be 8 ohms and in parallel it would be 2 ohms. Wired in series would not be as loud as parallel but it would be easire on the amplifier.