Help please! We're running our bassists 3/4 upright bass (Realist pick up) through her Hartke bass amp. She also plays a Fender Precision during the show. Switching back and forth and readjusting her levels during the performance is a pain as well as time consuming. We're trying to figure out a way to keep both instruments plugged in at the same time. We have tried both the Whirlwind Selector (Active A/B Switcher Box) & an ART SplitMix4 to attempt this fix. The problem is that the signal strength to the amp drops off dramatically requiring her to turn the hartke to 10 in order to get any usaable volume on stage. Ideally we'd like to have two separate channels going into one output and then into the hartke. We had hoped the splitmix 4 with it's individual volume controls would have worked ideally but the loss of volume was staggering. Any other little 2 channel whatcha ma jigs out there you folks can think of??? Preferably passive but powered would be OK. Thanks!