I see that the 1500D have 2 sets of speaker outputs. So the easiest way is to get dual 2 ohm, hook it up in parallel, then the internal are bridge for a final 1 ohm load.

What if I were to go with dual 1 ohm (1 sub) wire it in series = 2 ohm, then bridge the connection to the amp, will i get a final load of 1 ohm? I can't tell from the manual if the external outputs are bridgeable. Please confirm.

Thanks!

You're misunderstanding Mono amplifiers. The two terminals are NOT bridgeable. They're essentially the same terminal, internally paralleled.

So if you want a final 1 ohm load, you need to get the Dual 2 sub. You then have two options on wiring. You can wire each voice coil to a terminal, or you can wire the VC's together in parallel and run them to one terminal.