No you dont understand what clipping is at all. Its not originating from the sub, its the amp thats clipping. You clip the signal from trying to get more power out of the amp than the amp can provide which forces a shitty dirty signal to your sub which causes massive heat build ups. It doesnt matter what the subs are rated at, its irrelevant, its your amp completely maxed out and you trying to get more out of the amp. Its purely a weak amplifier issue, no relation to the sub's rms values whatsoever.
Basically you dont like how weak it sounds, you crank the gain up and now the subs sound like complete **** without getting any louder and you'll eventually blow them like that.
Either get a more efficient box design, A louder car, or electrical upgrades + 3.5k rms korean amp and wire to half ohm. After box rise your subs wont see much power at all so you are right now severely underpowering those subs if they really are rated for 1500 rms. Why wire to half ohm? because of box rise. Doesnt matter what the amp says, right now you are wired to 2 ohms you'll never get 1000 rms out of the amp, when the sub moves and the coil travels through the magnet, your impedance will change depending on the frequencies played.
Being wired to 2 ohms you are more likely seeing 4-8 ohms power out of the amp so more like 300-600 rms total for both subs which is severely under powered wich each sub getting less than 300 watts each. Its not because the amp is bad or under performing, thats just how physics and car audio works, you are getting proper power just at a much higher actual real world impedance. Go do a few true rms clamp tests in a few car audio competitions and you'll quickly see that you'll never get the 1 or 2 ohm claimed power rating out of any amp unless its a regulated power supply amp. Box rise is typically 3 x your wired impedance so thats why i'd recommend stout korean amps that can handle half ohm and you'll see around 1.5 ohm power out of them and they are usually underatted so you'll get the full rms power needed to fully power your type x