Simulation offers many advantages when designing analog circuits. Designers can explore alternatives quickly, without added cost or risk of hardware faults. However, it is challenging to use simulation as an aid during interactive debugging of physical circuits, due to difficulties in comparing simulated analyses with hardware measurements. Designers must continually configure simulations to match the state of the physical circuit (e.g. capturing sensor inputs), and must manually rework the hardware to replicate changes or analyses performed in simulation. We propose techniques leveraging instrumentation and programmable test hardware to create a tight coupling between a physical circuit and its simulated model. Bridging these representations helps designers to compare simulated and measured behaviors, and to quickly perform analytical techniques on hardware (e.g. parameter-response analysis) that are typically cumbersome outside of simulation. We implement these techniques in a prototype and show how it aids in efficiently debugging a variety of analog circuits.