Yes you can run a second sub. But you must not run your amp bridged. Just hook it up in normal stereo mode with one channel of the amp powering each speaker. My best advice to you however is to sell the sub you have right now and go buy 2 DVC (two 4 ohm voice coils) subs. You can wire them in parallel so that your amp sees a 2 ohm load. Then you will be getting the most from your amp. I am almost positive that the specs for the amp are wrong on the link you provided, It states that the total power output of the amp stays at 600 watts whether it bridged, stereo 4 ohm or stereo 2 ohm. I really doubt this is correct. An amp will usually make around 60 to 80 percent more power when seeing a 2 ohm load(depending on design and quality of the component). For example lets say your amp is 100 watts x 2 channels (200 watts total) RMS @ 4 ohms. It would produce between 160 and 180 watts x 2 channels(320 to 360 watts total) RMS @ 2 ohms.This is of course if your amp is 2 ohm stable(PLEASE MAKE SURE TO FIND OUT BEFORE YOU HOOK THIS UP YOU COULD FRY YOUR AMP IF IT IS NOT STABLE AT 2 OHMS.) You can usually find this out by looking on the amp itself near the speaker output terminals. If you cannot find the information there try contacting MTX directly. I hope this helps.
