check jl's web site-750 rms:fyi:
Technically you are both right. JL use to post that it was rated at 500 watt rms, but they have changed it to 750W (thermal power handling) on their website, However, if you look at the power chart, you can see that 500w is in the optimal zone, and 750w is in the black warranty void zone. I've personally have used a Alpine MRV-1002 600w at 4ohm and a JL 500/1 on a 10W7 and it was enough power. I wouldn't recommend anything more, definitely nothing at 1000w.
10W7 DRIVER SPECIFICATIONS
10W7-3
Free Air Resonance (Fs): 30.6 Hz
Electrical “Q” (Qes): 0.578
Mechanical “Q” (Qms): 7.647
Total Speaker “Q” (Qts): 0.537
Equivalent Compliance (Vas): 1.28 cu. ft. / 36.1 liters
One-Way, Linear Excursion (Xmax)*: 0.9 in. / 23 mm
Reference Efficiency (no): 0.171%
Efficiency (1W/1m)**: 84.3 dB SPL
Effective Piston Area (Sd): 59.8 sq. in. / 0.0386 sq. m.
DC Resistance (Re): 2.75 ohm
Nominal Impedance (Znom): 3 ohm
Thermal Power Handling (Pt): 750W
Driver Displacement: 0.09 cu. ft. / 2.5 liters
Net Weight: 30 lbs. / 13.6 kg