I mostly used powered monitors in mono, A/B'ing short looped snippets of my reference tracks by swapping a Benchmark DAC-1 output between pairs of identical monitors, each with a different power cord. After a lot of ear-hours, I'm now a believer that in this application there is an audible difference between typical 18 AWG and 14 AWG power leads, and a performance improvement with the MusicCord-PROs. With 18-gauge leads, effectively my "reference normal" for small monitors, the speakers sounded a bit thin, with less low end and less detail than with the ESPs. With 14-gauge leads, the bass presence improved over 18 AWG leads; warmth at the expense of reduced transient response. The MusicCord-PROs gave the benefits of both with still finer detail and a more "natural" sound. There was more depth in stereo with the ESPs; mixes sounded more like a cohesive whole and less a collection of parts.

What I heard was consistent and repeatable; significant, bordering on profound depending on the speaker. And, ESP recommends its cords for more than just amps and speakers. The MusicCord-PROs are thick and a bit awkward in use, and expensive at $165 for a 1.5m lead (the 16 AWG equivalent MusicCord runs $119). But, I'll have to let my aural memory blur before I go back to listening without them.

Review a power cord? Yes, and the ESP MusicCord-PRO is honestly a worthy subject for discussion. Michael Griffin, founder, president and design engineer at ESP, describes the motivation behind the product: "For dynamic peaks in particular, sometimes the amplifying equipment is just not getting enough current to reproduce the waveform accurately."

The wiring in between our breaker boxes and our outlets is typically flat with the ground lead in between the hot and neutral conductors; low magnetic/inductive interaction is in play. The typical Edison to IEC power cable is round and tightly bundled resulting in more interaction. Also, intuition would suggest that a move from a common power cord using 18 AWG wire to a larger gauge, say, 14 AWG, would yield more current capability, and it does, but Griffin says

The patented MusicCord-PRO approach uses an oversized 12 AWG ground wire as a core, spiral-wrapped with eight 20 AWG wires for a 14 AWG equivalent current capacity. Griffin elaborates: "As you go to smaller conductors, they have faster time constants. Of course, they don't handle as much current. By using multiple 20 AWG conductors (that have no audible phase distortion) in parallel, it's like taking these small conductors, with very fast time constants, and stacking them on top of each other.So you've got a very fast ramp up and drop off; AC current can flow faster. That's how you improve the transient performance." He adds that the ESP cables also have a braided copper RFI and EMI shield, offset by an inner jacket for improved EMI performance, particularly at 120 Hz.