I have been using a Demeter HBP-1 and Alembic F1-X with a Stewart 1.6 for a few months now. I've been wiring the Demeter output into one side of the Stewart and the Alembic output into the other side of the Stewart. For speakers I've been using two Goliath Jr III's (one connected to the Stewart Left side and one to the right side). I plug my bass into an A/B switch and choose either or both preamps. Many times I'd like to just use one of the Jr's or just my Bergantino. Would there be problem a using a Y-cable from both preamp outputs into one side of the Stewart or do these signals need to be isolated from each other? I considered another A/B box to switch the preamp outputs but I don't believe that you're suppose to make/break the input signal to a power amp (when it's powered up). Any suggestions?