Make sure your cabinets on Eleven Rack are off and check your speaker breakup. You shouldn't be getting fizz if you're doing everything right and using decent IRs. Take your time with presets also, it's very easy to get sounds but you wont be able to just take a preset made for Eleven Rack cabs and get results. Start from scratch with a JRC and a Treadplate M and play around a bit with the desired EQ, FX, etc; that you normally would just as you would a completely new amp & FX unit.