As Jim Austin primarily auditioned the CH Precision L1 using its direct-coupled balanced inputs and outputs with the gain adjust set to "0dB," the input impedance set to High, and with the preamplifier powered by the auxiliary X1 supply, I performed a complete set of measurements in that condition. (The manual says not to stack the L1 and X1; the supplied umbilical cable was long enough for me to place the X1 on the floor, well away from the L1.) I then repeated some of the tests using the unbalanced inputs and outputs, then performed the balanced input's…