Solid State Power Amp Reviews

Sound quality
For this assessment, the 200-system electronics perched on a four-tier, vibration-controlling Naim FRAIM rack. Standard NAC A5 speaker cables were used, among others (see the Associated Equipment sidebar), along with Naim Powerline Lite power cables, standard Naim interconnect cables, and on occasion, the Super Lumina alternatives. Power was supplied via dedicated low-noise, audio-specific spurs from an incoming mains connection for audio, hardwired to an exclusive breaker box.

The music source was the reference-level, "fully loaded" Naim ND 555 streamer powered by dual 555 PS DR supplies. Preamplification and volume-adjustment duties were carried out by the Townshend Allegri Reference passive control. My more recent experience is that running in Naim electronics is less prolonged than it used to be, perhaps due to a reduced reliance on tantalum capacitors. Previously, that final finesse seemed to crystallize only over some months of use. A few weeks of use was enough for the new 250 to largely settle down—but then it already had been out on loan for a month or two before reaching me.

Beginning with an ear to the loudspeaker, program absent, the powered system was absolutely silent—a good sign. Noise is always a critical issue. Even when present at very low levels, I find that it may subtly alter perception.

I rate the previous Naim NAP 250 model—the outgoing 250 DR—highly. I bought one, retail, from a dealer. But I was shocked and even confused by the latest iteration. This was so obviously a new sound, fresh and open, clear and transparent, in the low bass and the upper frequencies.

I had already put about some hours on the NAP 250 when I assembled my classic, decades-experienced, expert listening companions: Chris Bryant, Tony Faulkner, and Jon Honeyball. Their scoreboards were at the ready to record their opinions and ratings. At times, we returned to my extant 250 DR to observe the differences more clearly. We all individually and silently determined that the new NAP 250 offers a substantial improvement over its predecessor in numerous sound-quality dimensions.

To further this evaluation, I needed a clearer view of how the new power amplifier operated in a familiar system, here driven via my well-validated Townshend Allegri Reference auto-transformer control, which is single-ended internally but includes a pair of XLR-terminated inputs and outputs. Steve Reich was up first, with Sextet, Music for Mallet Instruments (CD, RCA 979138-21985), which I have played so many times that I feel certain I can recall every note and nuance of timbre, every potential soundstage dimension, its mesmeric drive, and all those intricate, kaleidoscopic details. I always hope new equipment might reveal additional detail, and this was the case with the Naim NAP 250. Compared with previous sessions, there was now an extra clarity to the soundstage, increased depth and width, but also a sense of enhanced spatiality where the xylophones and pianos shimmered and sang while those periodic, timing drumbeats were perfectly placed in the middle distance. The virtual soundstage was significantly enlarged, with more stability and solidity and crisper focus than before. There were also obvious gains in ambience and image depth.

In complete contrast, Joni Mitchell's "Blue," from the LP of the same name (WE A UK K441128), was rendered with that delicately subtle, introspective, gently rocking timing, plus a winning degree of intimacy, which drew in my listeners. Conversely, the densely scored opening track from Philip Glass's Koyaanisqatsi (CD rip to WAV, Nonesuch 7559-79506-2), served up from my Naim Unitiserve via the Roon Nucleus+, the Roon Core server, needs to sound majestic, spacious, and powerful, ideally with the electronics digging deep for subtle detail frequently hidden in the dense scoring. Sailing through this track, the pipe organ thundered appropriately in the low bass, yet the soundstage remained clear and spacious in the upper ranges. I have heard good power amplifiers at several times the cost which have offered a less convincing musical performance on this track. Sorry to say, it was also convincingly better than my own 250 DR.

I would describe the overall timbre as neutral, neither dim nor bright, the texture very fine grained, with an unusually clear-sighted transparency which enabled particularly deep and detailed soundstages. Jan Garbarek's "Evenly They Danced," from Rites (CD rip to WAV, ECM 1685/86, same delivery route as above), was entrancing, with a delicately nuanced and sparkling treble, and the eponymous opening track exhibited the correct degree of gloomy cavernous space, reaching back into a seemingly sonic darkness, accompanied by a stark, pounding beat in the low bass. On lesser amplifiers that particular percussive quality of this percussion section is frequently diluted, but not in this case.

I am fond of my extant NAP 250 DR, and in standalone mode it remains a great power amplifier with well-benchmarked qualities of fine timing, bass tune playing, solid rhythms, and spacious, well-focused stereo images, but this new version has certainly moved the goal posts. For the new version I am now reaching the 35-hour listening mark and my enthusiasm is undiminished, particularly for its recreation of a highly charged sense of spatial envelopment. Not wishing to preempt the next tranche of this 200-series Naim system review, I will nonetheless advise that this new power amplifier slotted into its place in the 200-system rack, with the streamer-pre and auxiliary supply, and was found to behave perfectly in situ. Highly transparent, it illustrated those fine differences between a panoply of connection modes, interconnect cables, and Balanced and SE operation. Likewise, a carefully configured and fine-sounding online streaming connection was clearly bested by files from a local hard drive source, served up by Roon—such is the analytical quality of this new power amplifier.

General observations included the sensation of deeper bass, which sounded like a half-octave extension. A 33Hz organ pedal note that previously was mildly audible was now rendered firmly with an appropriate growling texture. It played louder without fatigue. It rocked on jazz and rock and seduced with classical.

Replaying the Decca recording of "Summer" from Vivaldi's The Four Seasons with Alan Loveday, Neville Marriner, and the Academy of St. Martin in the Fields (LP, Argo ZRG 654), I was transported to my historic review experience with the Goldmund Reference turntable (in The Absolute Sound, 1988). This recording figured strongly in that project, helping to chart the complex setup and calibration sessions to a final point of excellence (footnote 3). Languid, flowing, shimmering with detail, and near mesmeric, the new Naim produced a captivating replay.

For rock, I turned to Sting on LP, Ghost in the Machine, playing "Spirits in the Material World." This sounded as punchy and connected as I have yet heard, upbeat and rocking, with that characteristic crisp clarity and engaging dynamics. It did not need to be played loud to be engaging.

Conclusions
The NAP 250 stereo power amplifier proved to be easy to install and drive. It is loudspeaker-load tolerant and offers unusually high electrical efficiency. To the surprise and delight of all who experienced it, the sound quality was remarkably improved in every parameter. It is undoubtedly a front-line performer.

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Footnote 1: JA measured 0.31 ohms, rising slightly to 0.32 at the top of the audioband. That would suggest instead a damping factor of about 26.—Jim Austin

Footnote 2: JA's measurements found that the NAP 250 easily exceeded this specification, but channel separation was not constant over the audible bandwidth. See the Measurements sidebar.—Jim Austin

Footnote 3: The report Martin is describing, which does not seem to be online, appeared in Vol.13 No.51 of The Absolute Sound. "At that time, Decca a short walk away, lent me a 38ips copy master [tape] of the Vivaldi," for comparison to the LP version played back on the Goldmund Reference, he told me in an email. Martin also said that for the current review, he listened to the very same copy that he listened to back then, on a Linn LP 12, his reference record player in 1988, when he carried out this Goldmund review.—Jim Austin