The NAD T757 produced ample power on our test bench trials, easily exceeding both NAD’s own “full-disclosure” power rating of 60 watts, all channels driven full-band, and its stated performance of 120 watts on the much more lenient single-channel FTC rating. Even with all 7 channels stressed, the NAD still delivered 75 watts, which is impressive.
Other results were for the most part excellent. The T757 fell a couple of decibels short of the theoretical ideal on our real-world, dithered-noise S/N tests, and its digital-to-analog linearity, while perfect down to –75 dBFS, was not measurable lower due to excess noise below that level, along with evident DAC muting at around –80 dBFS. My efforts to “hear” any D-to-A shortcomings on our very low-level, fade-to-noise test tones were futile, even with ’phones at quite high volume settings, so I am fairly confident in characterizing this as an anomaly of the test bench only. — D.K.
“More of what you want and less of what you don’t.” That might have been NAD’s credo in designing the T757, and it’s one I can subscribe to with considerable enthusiasm. The T757’s audio performance was entirely above reproach, and its “hands off the video” philosophy will serve most contemporary systems just fine. This refined receiver’s price is not insubstantial, but then again neither is its performance.
Dolby Digital Performance
All data were obtained from various test DVDs using 16-bit dithered test signals, which set limits on measured distortion and noise performance. Reference input level is –20 dBFS, and reference output is 1 watt into 8 ohms. Volume setting for reference level was –5. All level trims at zero; except for subwoofer-related tests, all speakers were set to Large, and subwoofer On. All are worst-case figures where applicable.
Output at clipping (1 kHz into 8/4 ohms)
1 channel driven: 141/211 W (21.5/23.2 dBW)
5 channels driven (8 ohms): 88 W (19.4 dBW)
7 channels driven (8 ohms): 75 W (18.8 dBW)
Distortion at 1 watt (THD+N, 1 kHz)
• 8/4 ohms: 0.07/0.07%
Noise level (A-wtd): –73.4 dB
Excess noise (with sine tone)
• 16-bit (EN16): 1.9 dB
Frequency response: 20 Hz to 20 kHz +0, –0.8 dB
Stereo Performance, Analog Input
Reference input and output level is 200 mV; volume setting for reference output level was –6.
Distortion (THD+N, 1 kHz, 8 ohms): 0.05%
Noise level (A-wtd): –89.1
Frequency response: <10 Hz to 140 kHz +0, –3 dB
Stereo Performance, Digital Input
Reference level is –20 dBFS; all level trims at zero. Volume setting for reference level was –6.
Output at clipping (1 kHz, 8/4 ohms, both channels driven): 119/178 W (20.8/22.5 dBW)
Distortion at reference level: 0.07%
Linearity error (at –90 dBFS): see notes
Noise level (A-wtd): –73.1 dB (see notes)
• with 96-kHz/24-bit signals: see notes
Excess noise (with/without sine tone)
• 16-bit (EN16): 2.2/2.2 dB
• quasi-20-bit (EN20): 19.1/17.8 dB
Noise modulation: 2.4 dB
Frequency response: <10 Hz to 20 kHz +0, –0.9 dB
• with 96-kHz/24-bit signals: +0, –5.8 dB at 44.1 kHz
Bass-Management Performance
Measured results obtained with Dolby Digital test signals.
Subwoofer-output frequency response (crossover set to 80 Hz): 18 dB/octave above –6-dB rolloff point of 83 Hz
High-pass-filter frequency response (crossover set to 80 Hz): 12 dB/octave below –3-dB rolloff point of 80 Hz
Maximum unclipped subwoofer output (trim at 0): 5.8v
Subwoofer distortion (from 6-channel, 30-Hz, 0-dBFS signal; subwoofer trim set to 0): 0.02%
Crossover consistency: bass crossover frequency and slope were consistent for all sources and formats
Speaker size selection: all channels can be set to “small”
Speaker-distance compensation: available for all main channels.
It looks like the subwoofer crossover doesn't quite add up - 12db/octave high-pass and 18db/octave low pass instead of 24db/octave. Does that mean there will be up to an extra 6 db output at 80hz if you set your subwoofer with 20-40hz test tones? More importantly, does it make a an audible difference in sound?