I listen not only in my private life to consumer systems but also as a professional sound engineer and sound technology journalist in my small but beautiful studio. There I mainly use multi-channel converters that can be sync'd by/locked to an external word clock input or run via coaxial S/PDIF, Toslink and AES11. Two-channel devices available to me were a Lavry DA11 and AD11, the former without, the latter with dedicated word-clock input. The A/D typically routes out the master output of my analogue mixer to transfer complete mixes into the digital domain. I monitored the Mutec reference clock generator with an Abacus 60-120D Dolifet amp and Harbeth Super HL5+ monitors via familiar commercial recordings plus my own productions.

My main studio converter is a ~€7'500 Swiss Merging Technologies Hapi. Its cards convert in both directions at a max PCM 384 or DSD256. In addition to analog connections, there are eight-channel AES/EBU, S/PDIF or ADAT optical via Toslink, word clock i/o and the actual connection to the computer via the professional AoIP Ravenna protocol. How did Hapi respond to the Mutec injection? It depended. In solo mode I couldn't make out any relevant sonic difference. It's in multi-device mode when additional converters connected to Hapi via AES/EBU and ADAT that the external clock minted clear sonic gains particularly in stage-related stereophony. Now multiple clock signals off the MC3+ USB sync'd all devices to the same clock signal in a star cluster.

Next up was a somewhat outdated audio interface called 896mk3 from US company MotU. This acquired a new lease on life as soon as the Mutec MC3+ USB imposed its clock signal. This significantly broadened and deepened the soundstage and generated greater image focus which was impressive with symphonic orchestra or church organ. The treble too responded positively by appearing a lot more transparent and clear during impulses. That all was dandy but not really that novel relative to other high-quality clocks I'd previously connected to the MotU. The real difference maker was Nano. I didn't expect the delta between the already high-quality clock of the MC3+ and Nano's 10MHz clock to be this noticeable. In fact, things seemed to take a big step forward in music. The phantom centre between the speakers appeared even more clearly tangible and recorded reflections more cleanly separated from their images.

Interim conclusion: For the MotU interface, clocking via Nano was the ultimate stem-cell rejuvenation. In a blind test I'd no longer recognize my MotU. The playback was that much better. However, it should not be hidden that the price for the two Mutec devices was approximately twice the original price of my converter.