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I also ran a comparison between a $7 generic Firewire cable and a $29 Monster Pro and could not hear the faintest difference, not even in my dreams. Yet if you feel adventurous, Esoteric offers a $750/1m i-link cable. I did not hear it but certainly hope it sounds impressively better. While on the topic of i-link and Firewire, do not expect to connect a computer directly to the D05 via Firewire to make it the most efficient way of playing PC/Mac files. The computer will recognize the D05 as a new audio device but stop there. According to Esoteric, the two communication protocols are different for "safety reasons" which I freely translate to "patents and royalty payments make it illegal to use the same communication protocols for computers and audio gear" (somebody correct me if I'm wrong). In either case, this is a missed opportunity if ever I saw one. I-link into the D05 certainly sounded far superior to any USB DAC I've ever heard - and by a New York mile. Enough said.

To round up the introduction of the P05, I should add that it accepts word synchronization from the D05 (recommended setup in the absence of an external clock) but also from any device outputting a clock signal at either 44, 88, 100 or 176kHz (beware as the D05 can also emit DVD synchronization signals at 48, 96 and 192kHz which won't be recognized by the P05 to cause a puzzling 'word error' message until you realize that you have set the source to the wrong sync frequency).

Which naturally gets us to talking about the matching D05 D/A converter. In faithful heritage from the D03, this new DAC features dual-mono balanced construction, using one balanced converter per side, each channel with its own dedicated power circuit for ultimate separation but unlike in the D03, the various circuits are not encased in separate internal enclosures. The D05 accepts dual mono balanced digital signals from the P05 (and P03, P01 as well as any player outputting digital signal in this fashion, which is relatively rare) plus coaxial and optical as well as the already mentioned I-link connection. A simple button on the face plate, duplicated on the remote, allows you to switch from one input to the other and as with the P05, the dual mono XLR inputs can be turned into two stereo XLR digital inputs for ultimate flexibility. As you go from one input to the other, you'll hear relays click, bringing in or taking out appropriate circuits to keep the active circuitry to the strictest minimum.

The D05 can send out a word-clock synchronization signal to one source (in most systems a P05). When multiple D05s are daisy-chained by i-link for multi-channel SACD playback, then one of the DACs is set as master and the other two as well as the P05 as slaves.
Obviously the D05 can also operate in the absence of word synchronization. The user may choose between a simplified or more elaborate jitter reduction circuit (labeled PLL1 and PLL2 respectively). PLL1 and PLL2 differ in more than one way but to keep things simple, PLL2 was designed to lock to clocking signals with very tight specifications (like Esoteric's own), the PLL1 to accommodate more erratic clocks. As Esoteric's technical manager put it to me: "The rule of thumb is that you should use PLL2 if the data is acceptably accurate to lock to. The Word indicator will flash green while locking. If it locks, it will turn the indicator light. If it can't lock, go to PLL1 and try again."

One element to remember is that the clock setting in the D05 is specific to each input. That makes complete sense and offers the greatest flexibility but if you put a new input to service (like switching from the dual mono input to the i-link between P05 and D05), you'll have to remember to reset the synchronization. You only do that once for each input as the D05 remembers the different settings. Similarly, if you change the source connected to a given input, you may need to change the synchronization method again to adapt to the specifications to this new source.

A potentially nice feature of the D05 that I'll explore more in the upcoming review of the Genesis amplifier is its variable outputs (both balanced and single-ended). Most people will set volume on their preamp and use the D05 for limited trimming - after all, 32-bit processing theoretically offers extra bits to throw away for attenuation without major impact on sound quality. In practice, small adjustments did not seem to impact sound quality at all. When it comes to major attenuation as in completely bypassing a preamp, that sonic assessment will have to wait until I have spent more time with the Genesis amplifier. I can already report that the attenuation is limited to -48dB before going mute. More annoyingly, the 1.5dB steps over most of the range make this feature quite impractical in real life (especially since the first step is actually 6dB, jumping from -48 to -42). Over my 89dB Ronins, this connection also did not offer enough gain into my amps to really listen at 'party' levels - which did not bother me much as I typically listen more subdued but your amplifier's input sensitivity (what input voltage drives it to full output) and overall gain factor will be highly relevant in any source-direct connection scenario.

The D03 does not offer this feature but I wish Esoteric had gone further still by implementing a true analog control from +9dB down to -70dB in 0.5dB increments. This would allow the D05 to serve as a no-compromise preamplifier in systems with only digital sources. Even if the final diagnostics confirm that sound quality does not suffer from the digital attenuation, the useful range is too limited to be truly useful.

Unlike with the SA60, there is no risk to connect both balanced and single ended outputs at once (one to a preamp, the other to a headphone amplifier for example). Again unlike the SA60, the balanced connection of the D05 is far superior to the single-ended one so there is very little incentive to use the RCAs. The difference was significant enough that I preferred connecting the D05 balanced to my MA2275 amplifier, then tap the signal single-ended from the amp's tape output to the headphone amp rather than going unbalanced directly from the D05.

Of course I left the best for last. The D05, like the APL player, utilizes the new dual-differential 32-bit AKM chip, albeit only one per side instead of the deliciously decadent ten of the APL. According to Esoteric, the D-05 is the world's first D/A converter incorporating this device which has 32-bit processing throughout all stages, including the digital filter and Delta-Sigma modulator. The analog processing of the DAC device features a completely symmetrical L/R channel layout. Each circuit component of the device has its own power supply to reduce crosstalk and interference. The device's internal clock circuit also has its own power supply, helping to reduce jitter. An incoming PCM signal from digital devices (CD transport, DBS receiver, digital tuner etc.) can also be upconverted to DSD.

Unlike with the SA60, upsampling to DSD was not my preferred setup for CD playback. It's not that this delivered results inferior to the SA60 but it exhibited the same slight softening of details. In the SA60, this soft-focus effect helped minimize the last bit of digital harshness to be welcome. In the D05, there is no harshness to minimize. Therefore the DSD 'soft blur' effect came across more as an extra veil than an improvement. I had a strong preference for 176kHz upsampling which struck the right balance of high-end smoothness, tonal richness, resolution and dynamics on most discs. After a number of A/B tests, I also came to conclusion that I preferred upsampling in the P05 over upsampling in the D05 as I found the resulting sound ever so slightly more engaging and tonally saturated (an admittedly extremely subtle difference - on many discs I could not distinguish).

One of the key features of the P05/D05 is this level of flexibility for CD playback - from no upsampling all the way to DSD with narrow or wide settings using dual mono XLR connections or I-link. In my experience, it will always be possible to find a configuration that will optimize the playback of any particular CD, from the hottest top ends (where I prefer 176kHz or even DSD upsampling with 'wide' filter setting through the dual mono connection in that case) to the most dynamically compressed (pick 88kHz upsampling and the narrow setting in the D05).

One critical element needs to be brought up before going into more detail on what I believe the sound of the P05/D05 to be. This combination is extremely sensitive to cable choices which can significantly modify how it sounds. I did expect analog interconnects to make a difference and they did. The player being quite resolved and capable of conveying subtle ambiance cues, any interconnect that impacted the reproduction of very low-level signals seemed to prevent the P05/D05 from reaching the full potential. From that standpoint, the Zu Varial was an ideal partner and allowed all the information to flow through unhindered while preserving the full tonal complexity of the music. Any other cable in house seemed to have some detrimental effect on the music, either on soundstaging or ambiance or tonal density.

As usual in our house, power cables had very little impact on the overall tonal balance or performance. The Zu Mother I used on the D05 did tighten up the bass a little compared to the stock cable but nothing of significance. A power cable swap on the P05 had barely any audible effect. My biggest surprise though, especially after the complete absence of effects from a cable swap on the i-link connection, was to find how impactful the choice of digital cable on the dual mono inputs could be to the overall tonal balance. When I first received the P05/D05, I did not have any XLR 110-ohm digital cable (they are not the same as 75-ohm balanced interconnects although those can be used but the results will be sub par). I therefore contacted a few people to see if I could get some assistance. Both Adam Decaria of Zu and Robert Lee of Acoustic Zen came to my rescue with their Zu Ash and mc2=Zen respectively. This is a review of the P05/D05 and not digital cables yet the differences were interesting and profound enough to warrant a sidebar on the next page.