im assuming thats a 2 ohm sub... thats why you're using the 600 watt rms figure for the amp.

JL's have a tendency to blow easily... so overpowering them wouldnt be recomended.

An Alpine Type R, Infinity Kappa or Kappa Perfect or Boston Acoustics Competitor and Pro series subs will all handle the 600 watts RMS, being you get the 2ohm (or dual 4 ohm) versions.

At 4 ohms, that amp is only rated at 300 RMS.

I'd personally pick a better amp too... maybe an Alpine MRD-M500.