I have an active Peavey Millenium and a Hyperdrive, and have no problems.
Never tried the pedal with a passive bass, although I know my bass is WAAAAAY louder than the passive ones at my practice space on the same amp settings.
I'd say just turn down on your bass and/or turn down the mix dial on the pedal.
On second thoughts, when you play normally through the Lomenzo, how high is the input indicator on the pedal? If your into the red when your playing then that could be your problem. You haven't mentioned trying that, give it a go. The higher I have the input, the more it clips, so try moving it down
