Solid State Power Amp Reviews

Ever since the company began trading in the early 1970s, Naim has embraced certain core engineering values. For good or ill, these have significantly differentiated their product line from the mainstream. Importantly, some of their connector choices have deviated from established hi-fi–industry practice.

Such ostensibly awkward decisions were not made on whims or merely to be exclusive. Take Naim's well-researched, early choice of the DIN specification, often combined with proprietary connection topologies and cable assemblies, which made their products less accessible and less compatible with the broader audio market. Naim products were best used in an all-Naim system.

Another, supposedly superior alternative was the use of cables with XLR connectors, which were (and continue to be) widely used by broadcast and recording studios, ubiquitous on microphone feeds and common in other interconnection contexts. These interconnections generally use a balanced, two-phase signal in a configuration capable of canceling "common-mode" interference. In a pro-audio context, reliability, hum and noise rejection, and vibration-tolerant connections are highly valued, indeed essential—but isn't this just what we want for high-quality home-audio connections?

Naim chose its less-common connectors for a reason. These connector designs made it easier for the equipment designer and installer to unambiguously configure the audio chain (ensuring, for example, that the stereo channels were wired in the correct left-right orientation and correct phase) and offered superior electrical and mechanical integrity. Furthermore, they conferred greater immunity to vibration. The classic European 5-pin and 8-pin DIN signal connectors locked reliably, mitigated vibration effects, and massively increased connection reliability.

Naim connectors provided some protection from potentially system-damaging disconnection faults. I vividly remember such a disaster from several decades ago, when I was rudely awoken in the dead of night by a faulty ground connection. With a terrifying roar, a pair of Wilson WATT-Puppy bass drivers crashed and burned in under a minute when a lightly tensioned RCA plug parted with its connector and drove a monoblock power amplifier to way above clipping. This would not have happened with DIN- or XLR-terminated cables, with their built-in locking facility.

Naim also defined a systematic grounding practice for an audio system, avoiding the ambiguity often encountered with multiple grounds and the consequent, uncertain results prevalent especially with low-output phono cartridges. With a single, hierarchical ground connection in an interconnected array of products, hum- and noise-inducing ground loops could be avoided. You may get away without such exacting ground practice; even so, following it improves sound quality by subtly lowering the noisefloor. These high-contact-force, vibration-resistant, low-impedance connectors also reduce the potential for harmonic distortion arising at contact interfaces.

Naim was not seeking to impose this off-beat connector practice just to be different or to sell more proprietary cables. Rather, they created a more reliable cable and connector environment where the sound quality of their audio systems could flourish. They supported and marketed these concepts through persuasive demonstrations of sound quality. The foundation of all this was extensive, self-critical listening tests of every part in the chain.

All along, Naim has been conscious of market pressures to increase compatibility with mainstream products without conceding the performance gains realized by its idiosyncratic practice. This led to some connectivity changes, many of which are expressed in the new 200 series. On the back panel of the new NAP 250, you'll find two conventional, balanced left and right XLR input connectors in place of the single, proprietary two-channel XLR connector found on the previous 250 DR.

The new NSC 222 streamer-preamplifier's phono input has the usual terminal for turntable ground. (Yes, it includes a phono stage.) Phono cartridges have small output signals, some very small, which render them, their cables, and connectors susceptible to contamination by mains-frequency hum. Naim has applied hierarchical grounding to connected audio systems. The NSC 222 (and also the ND 555 streamer/DAC employed in this review) has selectable grounding; you can choose the 222 as the "primary source" ground connection or, alternatively, set it to "float" via a switch on the rear panel. The result of floating the ground is to assign the primary ground to the turntable.

Such setup niceties will be explored in the second review tranche covering the NSC 222 preamplifier-streamer, augmented by that additional matching power supply, the NPX 300.—Martin Colloms