biggest difference between GK MB112 n GK MB115
 

if any of you have experience with this two amps or any of them i know the speaker difference between the two , but both of them are 200w 35lbs or less kind of the same settings , im concerned if u loose bass power by going 12" instead of 15"

I have both. Each is used for different situations, sometimes both together. The 15 has a tweeter and boost button and it can get much deeper/louder. I like it best with my P with flats. I think the 12 has a more balanced sound, not as much thump as the 15. I don't use the contour on either, especially the 12. I prefer my Ibanez acoustic bass with LaBella black nylons through the 12 on the floor. I usually run a Sansamp and tweak according to setup and each room. I like both of 'em! Bring a couple of basses to the store if they have both sizes. And, they each sound better giggin' live than in the store.

thanks !!!