I love the power to weight ratio of my Fender Rumble 500 combo and 2 X 10 extension cab, but it sounds muddy to me at times and lacks articulation. It seems like I'm not always punching through the mix in the upper registers with both horns on. I've gigged with it using a Rickenbacker 4001, a Jazz with roundwounds, a P with Rotosounds, and a fretless J. I generally use the "bright" setting. The "vintage" setting is all boom and mud. I've been exploring the option of using an external preamp into the effects return jack of the amp. I like the darkglass B7K. It sounds very articulate and reminds me a bit of an overdriven Marshall Super Bass. Then there's the Carl Martin Bass Drive which would run into the Rumble's preamp. I love the sound of my Ampeg SB12 Portaflex. I wish that I could have that tone with adequate power and light weight. Any thoughts on getting a nice warm but cutting tube tone from a class D solid state amp?