I'm new to this and bought a inifinity 1230w sub, it says its 4 ohm, what kinda amp do i need or recommend i wanna run the sub at 300watts

 

Pretty much any amp rated at 300wrms will be good because you don't have to worry about it being 2 ohm or 1 ohm stable. Unless the sub is dual voicecoil? In that case you would want to get an amp that puts out 300w at 2 ohms. If you wanna keep the infinity theme goin then i would recomend the reference 611a. Yes you would be over powering the sub but that is a good thing. Or if the sub is dual voice coil (srry, i am not sure wether that sub is or not) then the reference 311a would be perfect.