Integrated Amp Reviews

In 2015, the venerable Canadian audio company NAD introduced its soon-to-be-popular D 3020 integrated amplifier ($499), which combined 30Wpc output, streaming capability, and an onboard DAC in a slick, contoured case. NAD's latest D/A integrated also smartly combines trend with functionality, lifestyle convenience with technological advancement. The C 328 Hybrid Digital amplifier ($549) goes its older, smaller sibling a couple steps better in features, while reverting to NAD's traditional look: an unfancy box finished in a dark shade of matte gray with subtle white lettering and logo. Like the D 3020, the C 328 includes a DAC and Bluetooth connectivity, and adds to them a headphone amp and moving-magnet phono stage. Powered by a Hypex Universal class-D (UcD) amplifier module outputting 40Wpc, the C 328 appears, on paper, to be the entry-level integrated to beat, assuming it ticks all the boxes in the test that matters most: sound quality.

Over the past year I've reviewed entry-level integrated amplifiers that cost more but weren't necessarily as powerful as the C 328. The Heed Elixir ($1199) offered 50Wpc, a headphone amp, and MM phono stage, and ditto the Rega Research Brio ($995)—but neither included a DAC or Bluetooth. Does the NAD C 328 offer greater bang for the buck than those costlier components?

At first I was confused about the C 328's inclusion of a DAC. Does NAD assume that prospective audiophiles who want an integrated amp with Bluetooth also own an older-model CD player they'd like to pair with the C 328's higher-quality, Cirrus Logic CS42528–enabled DAC? Or is NAD aiming the C 328 at casual and serious listeners alike—those for whom Tidal and Spotify, not to mention their Sonos or Denon Heos streamer, are as important as their Vijay Iyer, Berliner Philharmonic, and Kendrick Lamar CDs? NAD's apparent goal with the C 328 is to give everyone what they want, recalling that 1940s catchphrase, "Is everybody happy?"

Design
The C 328 is perhaps the most minimalist-looking NAD product ever. On the slim front panel of its plain case of thin steel are only, from left to right: a Standby button, a ¼" headphone jack, left and right Source buttons for scrolling through options (TV, Phono, Coaxial 1, etc.), an oblong display, a Bass EQ button (it boosts the bass response by 7dB), and a large volume knob. That last item is notable for its pliant, almost squishy feel: according to Greg Stidsen, NAD's director of technology and product planning, it's made of ABS plastic, and actuates not a potentiometer but a "damped" rotary encoder. Volume adjustments are made in increments of 0.5dB.

The very small remote-control handset—it could almost hide behind a playing card—duplicates the front-panel controls and adds Mute, a Dim button for the display, Bluetooth playback, and On and Off buttons, which switch the C 328 out of and into Standby. Note that making volume adjustments is not for people in a hurry: Beginning with the volume at its lowest level, displayed as –79.5, it took me several seconds of turning the knob clockwise through many full revolutions before its volume reached an ear-friendly level of –4.5. A niggling criticism.

The rear panel of this slim integrated-DAC is more densely populated, some jacks resulting in a tight fit when neighboring RCA jacks are also occupied. From left to right: a Bluetooth antenna connection, two optical inputs, four pairs of RCA inputs (Coaxial, Streaming, TV, Phono), a Subwoofer out, a ground screw, a nine-pin port for attaching remote-control or firmware-update devices, two pairs of speaker binding posts, the AC power inlet and fuse bay, and the master Power rocker switch. The C 328 sits on four shallow, conical feet of hard plastic.

I asked Stidsen about the C 328's implementation of the 24-bit/192kHz–capable Cirrus Logic CS42528 chip, the Bass EQ feature (which reminds me of the ubiquitous Loudness button found on stereo receivers of the 1970s and '80s), and the core of the amplifier's power-output section, the Hypex Universal class-D amplifier module.

"We license the UcD technology from Hypex and build our own output stage that uses different FETs and reconstruction filters to allow higher current limits," Stidsen responded via e-mail. "We use our own input/driver stage and power supply. We get very close to NCore performance with the simpler UcD circuit. We are also able to get better than class-A/B performance with the added benefit of low power consumption."

Stidsen pointed out that, in today's world of mass-produced digital components with inherently lousy DACs, the C 328 can improve the sound not only of CD players but of anything with a coaxial digital output—"We use a very high-end implementation to squeeze a lot more performance from the [Cirrus Logic CS42528 DAC]," he wrote. "Other products using this same DAC have about 10dB less dynamic range than we achieve with the same part. This DAC is widely used in high-quality AVRs because it is 8 channels in one package. We [execute] this part as a 2-channel DAC by implementing a dual-differential configuration, which uses the extra channels to reduce noise and expand linearity, which improves audible performance."

And Bass EQ?

"Because we expect this amplifier will often be used with smaller speakers that have limited bass extension, we have brought back NAD's Bass EQ feature, a low-Q filter centered on 80Hz with about 7dB of boost," Stidsen wrote. "This gives just the right amount of 'heft' to small bookshelf speakers without adding chesty coloration to male voice."

Setup
I used the C 328 primarily with the components of my smaller rig, which includes a Thorens TD 124 Mk.I turntable with Jelco 350S tonearm and Ortofon Quintet Bronze cartridge, and Quad S-2 speakers. The turntable and electronics sit on a nondescript, two-tier shelving unit I found in my building's hallway. The speakers sit atop 24"-high metal speaker stands. For comparisons and variation, I brought in Elac's Debut B6 loudspeakers and my trusty LG BD550 Blu-ray player, the latter used as a transport. A Lounge Audio Copla step-up amplifier handled incoming phono signals from the Ortofon moving-coil cartridge into the NAD's MM-only phono stage. The most excellent Triode Wire Labs Single-Ended RCA interconnects and Tellurium Q Black speaker cables juiced signals over audio hill and dale, and an IsoTek IVO3 Aquarius power conditioner cleaned up the messy AC of my building's 1960s wiring.

Listening to Jackie, Herbie, Sonny, Hamilton
Alto saxophonist Jackie McLean's slightly sour, melodiously left-of-center playing is one of the joys of jazz. Not everyone digs McLean's frequently queasy tone, but his classic jagged, barbed 1960s compositions remain challenging, especially as delivered by the crème de la crème of 1960s jazz royalty across more than 50 recordings from such labels as SteepleChase, Prestige, East Wind—and, of course, Blue Note.