Disc Players

Joining the P1 to a pair of D1 DACs via Esoteric’s ES-Link is absolutely the way to go for best performance [see PM's Lab Report]. These employ HDMI sockets and cables in name only – so long as the P1’s ‘DAC type’ menu setting is defaulted to ‘ESL3’, the data type is a proprietary 8x upsampled/48-bit format including, it seems, DSD. The latter is handled natively only via the S400 i.Link (which suffers inordinately high jitter here) or via USB-B, up to 5.6MHz or double-DSD. Digital filtering occurs in the P1 prior to output over its ES-Link, the choice being a fast roll-off linear-phase FIR type [black traces, inset Graphs 1 and 2] or no filter at all [red traces]. The FIR option offers a full 120dB rejection of stopband images and a response flat to –0.23dB/20kHz but at the expense of ringing in the time domain. ‘No filter’ delivers a perfect impulse [red, Graph 1] but with a –3.2dB/20kHz treble roll-off and almost no attenuation of stopband distortions [red peaks, Graph 2]. Upsampling to DSD offers a lower in-band noise floor, traded for increased ultrasonic noise [blue infill, Graph 2], and no change in THD.

Within each D1 DAC, no fewer than eight AK4495 converters (the flagship of AKM’s Verita/Velvet Sound range in 2013) are addressed via a Spartan 8 DSP that delivers a pre-processed data stream split between DACs 1-7 and DAC 8. Esoteric holds a patent for this ‘plural DAC’ process [see https://patents.google.com/patent/JP6043052B2/en]. For the D1, the AK4495 DAC services both DSD and LPCM inputs but there is little technical benefit in upconverting LPCM (from CD or an external S/PDIF source) to DSD prior to conversion. Stopband artefacts are not removed while the characteristic spray of ultrasonic requantisation noise is added [see blue infill, inset Graph 2] – so the ‘numbers’ are arguably worse but you might still prefer the subjective difference! PM