Having experience with both a 70s OR120 and some Matamp stuff, I will say the Matamp is what you are looking for. My bassist has a Matamp (Green) GT150 that he wanted to use for both guitar and bass. IMO that amp doesn't have enough power to push bass well, but the guitar settings were killer. He used it briefly in a Lynard Skynyrd tribute band called Lynard Skinflute. Matamp will do classic rock just fine.