Предусилители — NAD C 658

The C 658 is a streaming DAC preamplifier from NAD's Classic Series, built around the BluOS platform and a modular design with two MDC expansion slots. It was priced at USD 1,649 in February 2020 and now costs USD 2,599. Digital conversion, MM phono amplification, a headphone stage and two-subwoofer bass management share one chassis.

Key specs that matter

NAD specifies an ESS ES9028Q2M DAC running up to 24 bit and 192 kHz, with a frequency response within ±0.3 dB. Line input sensitivity is 93 mV for 500 mV output at full volume, with an input impedance of 22 kohms and 100 pF, and maximum output exceeds 4.5 V at 0.1% THD. Output impedance is given as source impedance plus 240 ohms. On line inputs, THD is below 0.005% at 2 V and signal to noise ratio exceeds 106 dB IHF A-weighted. The MM phono stage has 1.44 mV sensitivity, accepts more than 80 mV, and keeps THD below 0.01%. The headphone output has 6 ohm output impedance, below 0.005% THD at 1 V and more than 110 dB signal to noise ratio. The chassis measures 435 x 100 x 405 mm and weighs 10.1 kg.

Engineering and use context

Inputs are two RCA line inputs, an MM phono input, two optical and two coaxial digital inputs, USB, and two-way Bluetooth with aptX HD, and there is no HDMI input. The outputs comprise balanced and single-ended pre-outs, two subwoofer outputs with a digital crossover and bass management, and a 6.35 mm headphone jack. BluOS handles streaming from online services and network storage, connected by wired Gigabit or dual-band wireless networking, and it also supports multi-room playback with other BluOS devices. The two MDC slots allow new modules, such as additional inputs, to be added later without replacing the preamplifier. The low output impedance of the headphone stage suits headphones of low impedance as well as high.

Pairing

The balanced XLR output drives power amplifiers such as NAD's M23 or C 298, while other stereo amplifiers can use the RCA pre-out. Both subwoofer outputs let one or two subs be integrated through the internal crossover. An MM cartridge turntable plugs straight in.

Alternatives

The NAD M66 is the Masters Series streaming preamplifier, adding an ES9038PRO DAC, HDMI eARC, an MM/MC phono stage and four subwoofer outputs at USD 7,199.