That 1600 watt peak power figure for your subwoofer can't tell you what amp you need. You need to know the maximum RMS power the sub can handle. And you need to know the impedance (ohms) of the voice coil(s). JBL GT5 series subs have an RMS rating of 275 watts. The GTO series handles 300 watts. The Power series handles 400 watts. The GTi series handles 700 watts. Some are single voice coil, so the impedance is fixed. Others are dual voice coil allowing you to wire them for different impedance loads.
For maximum performance your amp should be able to provide at or near the same number of watts RMS into the lowest impedance at which the sub can be configured. For example, if your sub is the Power Series Model number P1224, it has dual 4ohm voice coils and can be wired to present either a 2ohm load (parallel) or an 8ohm load (series). You want to wire the voice coils in parallel for the 2ohm load and select an amp that outputs up to 400 watts RMS into 2ohms. The Orion Cobalt CO8001
is just such an amp. If you have one of the GTi Series subs, a better amp would be the JVC Arsenal KS-AR75
which outputs 700 watts into 2ohms.
Hope this helps.