Looking back at our September 2014 issue, I think my review of the Triangle Signature Delta loudspeaker marked something of a watershed in the evolution of my taste in loudspeaker sound quality. For decades I have been a devotee of what might be called "British" sound: low coloration and, overall, a rather polite presentation, coupled with low sensitivity. The Triangle speaker opened my ears to what could be achieved with a very different approach: still-low coloration but high sensitivity, impressive clarity, and a hefty dose of what the late J. Gordon Holt called "jump factor," in which the leading edges of transients are neither smeared nor tamed. So when, last September, on a visit to Dallas and The Sound Organisation, the US distributor of Danish Audiophile Loudspeaker Industries (DALI), I encountered DALI's Rubicon 8 speaker (footnote 1), which had benefited from a low-loss design philosophy similar to the Triangle's, I asked for a pair for review.

Several seconds after I began listening to it, I knew that Theta Digital's Prometheus monoblock amplifier ($12,000/pair) was different from other amplifiers. The violins and brass were more dynamic, and had more pace. The orchestra sounded more three-dimensional, depicted in relief by a degree of hall ambience I hadn't heard when I played the same recording through my reference solid-state stereo amplifier, a Mark Levinson No.334.