Accuphase DP-100 Super Audio CD transport & DC-101 Digital Processor:
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'Round back are two digital outputs to choose from: S/PDIF on RCA (CD playback only) or the proprietary Accuphase HS-Link, implemented on a Cat-5 TIA/EIA 568A cable with an RJ-45 connector. The HS-Link is made up of four twisted pairs of copper wire, allowing plenty of bandwidth for security codes, left and right channels, and clock signals. SACD appears only at the HS-Link output, not the the S/PDIF RCA, and you cannot record or port the HS-Link signal into anything other than an Accuphase option card. Accuphase claims that the HS-Link will pass 400 megabits per second, with a theoretical burst-speed transfer rate of a whopping 1.9 gigabits/s.

You can use this proprietary link for all signals sent to the DC-101 (SACD/CD), or try an S/PDIF cable when playing CDs. I listened both ways and preferred the HS-Link, so for comparative listening purposes I usually "ported" the S/PDIF to the dCS 972 D/D converter or the dCS Purcell/Elgar. The Serial Copy Management System (SCMS) is implemented on the S/PDIF output, which prevents subsequent recording of a signal that has already been recorded once from a digital source.

Processing Department
The seemingly hewn-from-solid 46-lb DC-101 Precision Digital Processor comes standard with two option boards slotted into its rear-panel access ports. The first of these, the DIO-OC1, is a digital input/output board fitted with a pair of S/PDIF ins and outs on RCA jacks, plus another pair of digital ins and outs on TosLinks. Here's where you hook up a CD-R burner, a DAT machine, or whatever else you're using to make recordings. The second standard board, the D12-HS1, is the double-slot HS-Link input. These boards occupy slots three through five on the left rear of the back panel; three more bays sport cover plates but stand ready, willing, and able to accept a wide variety of additional option boards.

Also on the rear panel is a phase-invert switch, an important feature that Accuphase's DP-75V lacks. The DC-101 adheres to balanced pin three "hot" rather than pin two, so you have to compensate for absolute phase somewhere else in the system. Yes, yes, I acknowledge that many recordings are all screwed up in this regard, but some baseline is necessary for evaluations. Two pairs of balanced connections on XLRs and two pairs of RCA single-ended jacks finish off the rear panel, plus an IEC mains-in receptacle.

Around front, you get that same sumptuous build quality and Nextel chassis coating embodied in the transport. Still, once you get past all the gold, the DC-101 looks relatively understated and minimalist. On the substantial faceplate, besides the Power button, there are only two other controls, on the lower right: Input Selector and Output Level. And yep, the DC-101 can be used without a preamp, directly into a power amp that has its own volume control. I tried it that way...very interesting. But indulge me while I keep you in suspense a bit longer.

Pressing the Input Selector switches the DC-101 into External DSP mode (for use with the Accuphase's DG-28 Digital Voicing Equalizer, $8200, reviewed in Vol.21 No.6 but not used for this review); pushing the Output Level knob selects menu subsystem choices, such as changing input names or resetting default parameters. You can also rotate the Input Selector knob to choose alphanumeric characters to customize the input display. LEDs in the display reflect External DSP Active, Input, and Phase.

The digital circuitry in the DC-101 comprise a level control and six single-bit Multiple Delta Sigma (MDS) DACs per channel, their output routed through a three-pole analog low-pass filter, with additional buffering for balanced line-level output. Accuphase engineers write their own algorithms for DSP and noiseshaping.

The DC-101 is but one of several components you might use in conjunction with the DP-100 transport. Using the HS-Link output and various combinations of the input and output option boards that slide into the modular Accuphase gear, you might include a DG-28 Equalizer, the previously mentioned DP-75V, or several appropriately optioned Accuphase amps and preamps. Walk this way...

Be you an upsampler or an oversampler?
Okay, we know the DC-101 is an SACD converter, but it's also said to upsample when decoding a 16/44.1 "Red Book" CD datastream—just like the DP-75V. I noted that there was no 24/192 logo on the DC-101's front panel. When pressed about these matters, importer Art Manzano assured me that the DC-101 used the latest 24-bit MDS DACs, as does the DP-75V. Pressed further about the differences between upsampling and oversampling, he mumbled something about marketing mumbo-jumbo by another company that's confusing everyone, and faxed me a copy of an e-mail from Kelly Kawakami of Accuphase, Japan (kelly@accuphase.co.jp), evidently written in response to someone else who'd asked much the same question.