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Time for a cross check. At €2.900 a realistic competitor, my Abacus Ampollo amp sounded decidedly different. The first impression was of greater bandwidth. The treble was brighter, the bass a tad more substantial. Large voltage swings (here I often refer to early Nada Surf but also orchestral symphonies) had more immediacy and gush where the NAD played it more compact. To avoid misconception, the NAD clearly was super quick across the board. But when time came to displace maximal air with 0-to-100 suddenness of roaring guitar volleys, the Ampollo had the edge. What I preferred with the NAD was its becoming warmth. How the world had turned upside down. A digital amp which sounded warmer than a 'normal' type? Strange but so. To overwrite and get anthropomorphic, the NAD humanized, the Abacus went to the recording studio.


A few words about the optional analog module. Its line-level option seemed highly transparent. Here I fed the Audiolab 8200CDQ's analog outputs and recognized some of its typical handwriting which is lightly emphatic on high but otherwise similar. Due to my phono setup being rather modest, I'll save you any comments on NAD's phono input. I also confess to inner reluctance envisioning a micro-volt signal carefully extracted from a mechanical medium whilst being converted to digital. Brrr. But nice that it's possible for those made of sterner stuff than I.

NAD's C390DD is somewhat of a brain tease in how its circuit concept contradicts popular expectations. To say it clearly, NAD proves how ongoing reservations about class D are groundless. Au contraire, a fully digital machine can do warmth and refinement, detail and color. For me this was the encounter's biggest surprise. I was particularly taken with the fast well-timed rhythmic fidelity even if competing types offer a bit more on macrodynamics. Overall this is a very long-term capable machine whose expansion modules should accommodate all segments of its target audience.

Psych profile
• The C390DD dominates with a trick mix of tonal mildness and rhythmically adroit pep.
• No studio kit but an amp with a musical heart. In the low bass other amps are grippier and reach lower but come in second on timing. The mids are clear and seamlessly integrated. The upper registers are milder yet sufficiently clear and airy.
• The virtual stage is astonishingly deep and realistically broad.
• Resolution is good, microdynamics are brilliant but more massive voltage swings can be had elsewhere for similar coin.

Facts:
• Category: class D digital integrated
• Options. €299 DD AP-1 analog module with phono, €249 DD HDMI-1 module
• Digital inputs: 2 x USB passive storage, 1 x async USB 24/96 for PC/Mac, 2 x coax, 2 x optical, 1 x AES/EBU
• Outputs: 1 x optical, 1 x coaxial, 2 x pre-out, biwire terminals
• Dimensions and weight: 131 x 435 x 388mm HxWxD, 7.7kg
• Output power: 2 x 160 watts into 8/4 ohms
• Warranty: 2 years
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