measured the performance of the Audio-GD Vacuum HE1 XLR with my Audio Precision SYS2722 system, checking some of the results with the magazine’s APx500 analyzer. Although this preamplifier has both balanced and single-ended inputs and outputs, HR told me he exclusively used the single-ended input and output so he could use the same unbalanced interconnects with the HE1 XLR that he used with his other preamplifiers. I focused primarily on the preamp’s single-ended
