I would go with a Crate CPM8FX which is a powered mixer throwing 2x300 watts to 4 Ohms. It gives you 8 channels with PFL, Phantom Power, 2 Auxes plus a dedicated internal effects buss, 2 inline EQs for Mains and Monitors, and fairly musical channel EQs. But save your old amp for either a stereo or a seperate pomered monitor set-up. (Remember that if the amp specs to 4 0hms it means only two 8 Ohm speakers should be connectred to that side). I am unfamiliar with the Carvins, but the Crate can be had for around $500. You lose alot of flexability when you go with a box mixer, and the market is now producing some fairly decent powered mixers. Good Luck