It is possible to connect an external switch to Flashback Delay 2 stereo input, and control the tap tempo. - The switch must be a momentary single switch. There are many models on the market that can be used. But you will need a special cable to make them work with Flashback Delay 2- The cable: the tap will be triggered by closing the ring contact of the flashback input. So you need a custom cable that will connect the Ring of a TRS jack to the tip of a TS jack. The Tip on the TRS side should be left without connection. You can also use a standard insert cable (or Y-Split cable) and connect the TS jack that is connected to the Ring of the TRS jack, while the other branch of the Y-cable is not connected - See diagram belowsY-Split or insert cable: Custom Switch and cable
Keywords: What kind of switch and cable should I use to tap the tempo on a Flashback Delay 2?