Aloha From Hawaii... I'm the "old guy" newbie that initially seeked comments and/or advice regarding Hartke cabs with an Ampeg SVT-4 Pro head. Mahalo (thank you) to all of you who responded, as your replies were taken to heart. Now I intend to throw you all a curve ball with this: I totally took a right turn into the pineapple field! I did a ton of research on the I-net and discovered Jim Bergantino. I read about him and his company, soaked-in as many comments I could find... and most all were highly positive, spoke with John at Bass Emporium down in Austin, TX, and now I have an NV215 (2 x 15" + 1 x 6") on it's way here to paradise. This cab is costing me some serious $$$, plus shipping to Hawaii, so I've now found myself looking for an economical, yet "worthy" amp to drive this cabinet. The cab is rated 600w @ 4 Ohms. I found an "affordable" amp that has now sparked my interest: SWR's 550x. It's supposedly rated 550w @ 4 Ohms... I welcome any testimonials, thoughts, and/or advice... Mahalo!