Denon's AVR-4308CI impressed, with very good power results, and virtually perfect noise and linearity performance. Power with stereo channels driven handily bettered Denon's 140 watts spec, and performance with 5 channels driven was only a scant half-dB shy of that mark, at 126 watts. S/N on PCM signal was spot on the theoretically "perfect" mark on our dithered-silence test, and a couple tenths "better than perfect" with Dolby Digital signals. This is probably a lab-only vestige of a meaninglessly tiny least-significant bit error; nevertheless, linearity at -90 dBFS was effectively perfect, and our "excess noise" results were the best I've measured. (Analog-domain noise at the multichannel input was outstanding as well.)
The 4308CI's only technical issue was subwoofer output that, with the master-volume at reference-level and the sub-trim at 0, was on the brink of digital-clipping and measured 3.4% THD when driven by a 6-channel full-scale 30 Hz signal. This is insignificant in real-world terms, for several reasons. First, you can simply dial in a couple dB more (analog-domain) gain at your sub and back the receiver' sub-trim down a corresponding amount to avoid stressing it (probably a good practice in any setup). Second, actual entertainment programs almost certainly never, ever call for full-scale output from all 5.1 channels simultaneously, and surely does not do so other than very transiently. And, finally, audible effects (if any) from sub-signal clipping are inherently mitigated by the fact that the driver/enclosure combination typically roll off substantially at higher frequencies, where the harmonic content of sub-frequency signal distortion naturally occurs.
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 -4. All level trims at zero, except for subwoofer-related tests, all speakers were set to "large," subwoofer on. All are worst-case figures where applicable.
Output at clipping (1 kHz into 8/4 ohms)
1 channel driven: 171/280 W (22.3/24.5 dBW)
5 channels driven (8 ohms): 126 W (21 dBW)
7 channels driven (8 ohms): 111 W (20.5 dBW)
Distortion at 1 watt (THD+N, 1 kHz)
8/4 ohms: 0.02/0.03%
Noise level (A-wtd): -75.9 dB
Excess noise (with sine tone)
16-bit (EN16): 0.2 dB
Frequency response: 20 Hz to 20 kHz +0, -0.2 dB
Reference input and output level is 200 mV; volume setting for reference output level was -4.5.
Distortion (THD+N, 1 kHz, 8 ohms): 0.004%
Noise level (A-wtd.): -92.1
Frequency response: <10 Hz to 115 kHz +0, -3 dB
Reference level is -20 dBFS; all level trims at zero. Volume setting for reference level was -4.
Output at clipping (1 kHz, 8/4 ohms, both channels driven): 155/233 W (21.9/23.7 dBW)
Distortion at reference level: 0.02%
Linearity error (at -90 dBFS): 0.1 dB
Noise level (A-wtd): -75.7 dB
with 96-kHz/24-bit signals: -88 dB
Excess noise (with/without sine tone)
16-bit (EN16): 0.0/0.2 dB
quasi-20-bit (EN20): 7.6/7.5 dB
Noise modulation: 0.2 dB
Frequency response: <10 Hz to 20 kHz +0, -0.2 dB
with 96-kHz/24-bit signals: <10 Hz to 43 kHz +0, -1.3 dB
Measured results obtained with Dolby Digital test signals.
Subwoofer-output frequency response (crossover set to 80 Hz): 24 dB/octave (approx.) above -6-dB rolloff point of 80 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): 4.3v
Subwoofer distortion (from 6-channel, 30-Hz, 0-dBFS signal; subwoofer trim set to 0): 3.4%
Crossover consistency: bass crossover frequency and slope were consistent for all sources and formats
Signal-format consistency: consistent for all applicable formats
Speaker size selection: all channels can be set to "small"
Speaker-distance compensation: available for all main channels.
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