Those speakers are pretty flat down to 48hz. 3db down. I wouldn't expect to much bass below that. You might try positioning them in the room to add more bass, closer to the corners etc. You know it might take a while to just get used to the bass, it might be better then you think, more tuneful, more musical. I think the last thing I would do is buy an amp just to get more bass out of your speakers. I would be looking for more music.