Marantz NA 6005 Network Player
It’s also important to note that music signals don’t get as high as 0dB, due to the necessity to leave some headroom when recording, so you won’t ever run into any 0dB-level signals when playing back recorded music from any medium.
Graph 3, which shows distortion at –10dB, shows the level of distortion you could expect when playing typical music tracks. There’s only a single harmonically-related component at –123dB (0.00007%). At a level of –20dB, even this component has disappeared, so there are no distortion components visible above the noise floor at –140dB. Note, too, that the level of the sampling-related artefact has dropped to –129dB (0.00003%).
Distortion at very low levels was excellent, as shown in Graph 6, which shows distortion at –91.24dB and Graph 7, which shows it at –90.31dB. Other than the slight difference in level, the difference between the two test signals is that the one at –91.24dB has not been dithered, whereas the one at –90.31dB has. The improvement in distortion is the reason
all music stored digitally is dithered. The only disadvantage to dithering is a slight increase in the level of the noise floor. You can see that without dithering the noise floor is well below –140dB, whereas with dither added, the noise floor sits just above –140dB. Since this level of noise is well below the level of electronic noise of most hi-fi amplifiers, it’s of no consequence.
The IMD result was interesting, because the immediate sidebands are extremely low, and there is a high-level component at around 25kHz that’s just 40dB down and another at around 26kHz. This is fairly atypical behaviour, but because they’re well above the limit of human hearing, they’re merely interesting artefacts of the particular DAC Marantz is using, and presumably related to the signal at 15kHz. The signal that is usually present that you don’t want to be audible is the difference signal down at 1kHz, and you can see that it’s around 125dB down, which is more than sufficient. The same sampling artefact is obvious when the NA6005 is reproducing a single 20kHz tone at 0dB, though this time it’s just a single component at 25kHz, but at –37dB.
Overall THD vs. Frequency is shown in Graph 11 for both a –1dB signal (red trace) and one at –20dB. The levels are very low, and also uniformly low across the audio band, so excellent performance again from the Marantz NA 6005.
Linearity errors were very low, as you can see from the tabulated chart, averaging around 0.02–0.04dB at around –60dB and around 0.04–0.06dB down around –90dB.
Overall wideband signal-to-noise ratios were very good, as you can see from the tabulated figures, with Newport Test Labs measuring 97dB unweighted, improving to 107dB A-weighted using CD standard signals, and 114dB CCIR-RMS weighted when using 24-bit/48kHz (AES) test signals.
Power consumption was measured at 16.98-watts when the unit was operating and at 3.42-watts when it was in standby. This slightly higher-than-usual standby consumption suggests that despite being in standby, wi-fi and Bluetooth are still operational so the unit can be ‘woken up’ remotely. Although this is obviously very low power consumption, it does mean you should turn the unit off completely when you won’t be using it for long periods of time.
Superb performance all-round from the Marantz NA 6005. Steve Holding