Making the choice between ultralinear or triode mode will be as much (if not more of) a matter of your loudspeaker choice as it is of personal taste or the music in play. While you may be tempted to use ultralinear for louder listening and triode for lower volumes, over the years I’ve found that more often than not, at quieter volume settings, ultralinear provides the extra dynamics and inner resolution that are necessary to breathe life into a softer presentation.
My Von Schweikert Audio VR-55 Actives have a comparatively low 88dB sensitivity, but present a fairly stable 8-ohm load, making them relatively easy to drive. With them, the added warmth, more pronounced midband, more laid-back presentation, and somewhat less focused and slightly larger-than-life imaging in triode mode simply couldn’t match the more controlled and accurate microdynamics and higher resolution of inner detail that I experienced in ultralinear mode. Though triode mode offered a lusher, more organic balance overall, for me, in my system, it wasn’t even close. Once that became clear over repeated comparisons, I kept the amps in ultralinear mode for the rest of the review. Your experience will likely vary, so take advantage of the freedom of choice and experiment.
Once fully run in, (I gave them a full two weeks in this case), high-frequency performance opened up considerably, now offering greater and more refined extension and providing a more convincing sense of air and shimmer on cymbals, upper-octave strings, and winds. This attribute was readily noticeable on classical pieces like the Bach Violin Concertos and Double Concertos [Philips] or The Three-Cornered Hat [London].
Midrange was rendered, as you’d expect, with almost reach-out-and-touch texture, rich and vibrant tone color, realistic bloom, and a faithful sense of dimensionality and space. In this regard, these PrimaLunas are the embodiment of the characteristics that make valve amplification so intoxicating.
It was the deepest octave-and-a-half, roughly from about 65Hz down, that enjoyed the greatest sonic advance. The slight limitation that the HPs had exhibited when new all but vanished, and their response, all the way down into the 20Hz range, was much better defined. They now had a much firmer, more effectual grip on the deepest bass, giving them an amazing sense of graceful power.
This was clearly exemplified early in “Three Wishes,” from Roger Waters’ Amused to Death [Analogue Productions]. As the track picks up momentum, the QSound voice of a Genie fills the room—surrounding and engulfing you. And it goes deep! Still fresh from the boxes, that voice was generated only toward the front of the room, with very little of the powerful underpinning that makes it so creepy. Post run-in, the envelopment was much more complete, easily extending to behind my listening chair. And the weight of the voice was back, convincingly enough to make me shudder, as this track normally does. The recording evokes a visceral reaction, one that the Premium HP amplifiers were quite comfortable generating.
With something like the organ work from the second movement of Saint-Saëns Symphony No. 3 [Reference Recordings], the PrimaLunas had more than enough authority to convincingly create the power that loads the room with the lowest, sustained organ notes. Though still not as authoritative as the best solid-state bass, they were, nonetheless, very well extended and articulate, showing remarkable transient capability and excellent pitch definition, especially for a tube amp in this price range.
Though overall transparency was not astonishingly see-through (the amps do come up shy of the best resolution and transparency attainable), the HPs’ ability to render fine detail was more than merely convincing. Key-fingering on instruments like sax or clarinet was revealed cleanly and accurately. While you might be tempted to assume that such sounds would always be clearly and honestly rendered, such micro-detail is not always this finely presented.
What I found to be the HPs’ most remarkable strength was their ability to render dynamic attack and maintain scaling, from very quiet through much more boisterous volume settings. Respighi’s Feste Romane/The Pines of Rome, with Lorin Maazel conducting the Cleveland Orchestra [Mobile Fidelity UHQR], was goosebump-raising—so powerfully, cleanly, and accurately did the HPs reproduce orchestral dynamic swings. This extraordinary dynamic capability is yet another stirring asset of these amplifiers.
Spatial recreation was downright magical, especially when I was listening to something with an enormous and/or clearly delineated acoustic, like Falla’s The Three-Cornered Hat or Harp Attack [Alligator LCD 4790]. The soundscape on The Three-Cornered Hat is enormous, with expansive and detailed sonic queues, cavernously deep and wider than your room when your system is up to the challenge. Harp Attack features the voices of Carey Bell, Billy Branch, James Cotton, and Junior Wells, each playing a different keyed harp (harmonica). In the opening cut, “Down Home Blues,” the four men are lined up left to right across the stage. As they take turns soloing, both their location within the soundstage and the resultant sounds of their voices and harps were vibrant and lifelike, with remarkably nuanced pitch, and so well recreated in space that, with eyes closed, you might credibly believe the four were standing in your room!
Prior to inserting the PrimaLunas, I had been using either the Pass Labs XP-20 ($8600) or my reference Dynamic Sounds Associates Pre I ($16,500) preamplifiers. Time to add the DiaLogue preamp to the mix. As they had been run in at the same time, though in a different system, resolution was excellent, and in fact, much better than I had expected.
Soundstaging was finely and accurately layered, and images were rock-solid in location and stably placed, if somewhat larger than life. Centrally located images seemed less affected by this, but instruments to left and right of center, and especially those deeper in the soundstage, tended to be generated with a slight increase in size. I first noticed this with “Peggy’s Kitchen Wall” from Bruce Cockburn’s Stealing Fire [True North]. Bruce’s somewhat forward and central voice was still rather faithfully imaged, while the somewhat elevated-to-each-side and deeper-into-the-soundstage voices of the backing vocalists were slightly more inflated, and rendered with a bit less fine individualization. While this attribute persisted throughout the rest of my audition, it was minor and may not even have distracted me had I not been aware of the more focused and clearer individuality rendered by my reference preamplifiers.