Legacy is about the worst choice you can make. They are utter garbage, flea market junk. That "2600 watt" amp probably doesnt even make 1000 watts. Its a fake power number. Only look at RMS ratings. Even then, cheap companies inflate those, too.
You get what you pay for. Dont cheap out on the amp. If you want a match with brands, get something like a kicker zx1000.1 or zx1500.1
If you cheap out and get some flea market brand, it wont make a lot of power, and it will blow up, and you will just have to spend more replacing it.
PS you need a 2 ohm stable mono (1 channel) amp for these subs, since they will all be wired in a series/parallel configuration @ 2.66 ohms.