Vintage

The logo declaring 'Super Linear Converter' on the DCD-600's fascia relates to a single (mono) 16-bit PCM56P DAC from Burr-Brown driven via the 2x oversampling filter in Sony's CXD1135 DSP. The 'twist', if there is one, comes from Denon's use of an additional sample-and-hold circuit on the left channel to normalise the interchannel phase shift that would ordinarily occur with a time-shared DAC. Otherwise the performance of this player is similar to that observed with Sony's CDP-C5M [HFN Feb '21] which employed the same converter. However, Denon's choice of 2x filter is distinct and contributes to a response that's flat to within +0.4/–0.1dB (20Hz-20kHz), shows modest ±0.08dB in-band ripples [see Graph 2], and time domain 'echoes' closer to a minimum phase or hybrid filter than the more common linear phase types of the period. Stopband rejection is 63dB but neither the filter, nor Denon's additional 'trimming', improve fundamentally the low-level linearity of the DAC which shows a +2.1dB compression at –80dBFs and is 1-bit adrift at –90dBFs (Burr-Brown spec'd this DAC with a 15-bit monotonicity).

The analogue filtering suppresses HF distortion harmonics so that THD at 20kHz is lower than that through the midrange below –20dBFs [0.0022% vs. 0.013%, see Graph 1, below]. Otherwise the output level is close to the 2V 'standard' at 1.93V although the 955ohm source impedance is a little high and the A-wtd S/N ratio is some 10dB behind modern budget players at just 95.3dB (but comparable to that achieved by Sony's CDP-C5M). Stereo separation is good to ~85dB (20Hz-20kHz) but jitter is roughly double that seen from the CDP-C5M at 480psec and with sidebands that are data-induced rather than PSU-induced – the latter are typically less subjectively irritating. PM