A blind A/B comparison exploring whether the SPL Crimson 3 and Audient iD4 produce audible differences in real-world recordings. All tracks were recorded in mono using a matched pair of Neumann KM 184 microphones. For selected recordings, the microphones were swapped between the interfaces to minimize the influence of small differences in microphone position. Multiple listening rounds are used to reduce the influence of chance and perceived differences that may not be consistent.