I need help on getting a new amp. Right now I own a Peavey TNT 115 which sounds good but is too heavy to lug around. I'm playing two different types of music on my bass(Fender Mex. Jazz). One is a folk group. So I thought about getting a small combo amp of 60 to 75 watts. This would also serve as my practice amp. The other group I play with is a hard rockin blues band. We'll be playing bar gigs mostly. I currently use the guitar player's bass rig which is an SWR 400s with two 4x10 cabs. It sounds good but do I really need that. The other night I heard a Mesa Walk About(?) with a Bag End speaker and that sounded great. I'm basically confused about two things. One is how much power do I really need without overkill. And secondly, I still don't understand the different wattages because of 2,4 or 8 ohms. Is there a primer somewhere that will help me? Thanks.