Hello all. I need advise on what is prudent to do. I already own a Hartke 2000 bass head and an Ampeg SVT410HE cabinet. The Head is rated at 200Watts at 4ohms, and my Ampeg cab is 240 at 8ohms. The whole set is actually working at 120wats due to the overall impedance. Im planning to buy an extra cabinet to better handling the Low B, but im undecided between the 18" or 15", because of terms of efficiency and deepness. I already have the punch of the 4x10, but need better lows. Summing up that cab, the amp would put 200watts for those two cabinets. Wich desicion is wiser?? I need lows but dont have power to spare, so a 18 seems very unefficient, and a good 15" cab design could compensate the deepness of the 18" Any suggestions?