Beschreibung
PS Audio Digital Link II Gen 2 D/A Processor. Fabulous, working unit complete with 5.5 power cord. Some minor surface scratches as shown in the photos. Following is a review from Stereophile.com from 2019 (first published in 1992): The Digital Link II shares the same appearance as PS Audios SuperLink and UltraLink processors, but has a 4-shorter chassis. The ¼-thick front panel uses PS Audios familiar touch-sensitive switches that turn the unit on and select between coaxial and optical inputs. LEDs above these switches indicate when the unit is locked to the digital source. A third LED illuminates when power is applied.The rear panel features a pair of high-quality, gold-plated RCA output jacks, RCA digital input jack, and Toslink optical input jack. A four-pin jack accepts DC from the outboard power supply, a 4.5 by 2.75 by 2.5 black box.Technology Although I couldnt get inside the power supply, it reportedly contains a single large transformer. Once inside the Digital Link, the stepped-down AC is rectified, filtered, then regulated by four three-pin regulators. Like other PS Audio converters, the Digital Link has lots of filter capacitors (a total of 18,000µF) distributed around the board.The circuitry is contained on two pcbs: one handles the digital inputs and input switching control, the other is the main board containing the digital and analog circuitry.The input receiver is the 16-bit Yamaha YM3623B, but implemented with the jitter reduction circuit developed for the UltraLink. Digital filtering is provided by the 8x-oversampling Yamaha 3434, a small and inexpensive filter chip. A pair of Analog Devices AD1860 18-bit DACs perform D/A conversion. The AD1860s are the premium K version, selected for best low-level linearity and lowest THD. The DACs are matched between left and right channels, but no MSB (Most Significant Bit) trimmer is included.Like the SuperLink, the Digital Link II uses passive current-to-voltage (I/V) conversion. PS Audio is the only company I know of that doesnt use an active I/V converter (usually an op-amp). The current-to-voltage stage takes the DACs staircase current output and converts it to a voltage. In the Digital Link II, this stage is nothing more than a 150 ohm resistor connected to ground. The advantage of this technique is one fewer active device in the signal path, but at the expense of higher noise; by Ohms Law, using a low-value resistor means a lower voltage, therefore requiring extra gain in the line stage.The direct-coupled output stage is based on a Precision Monolithics OP37 op-amp (one per channel). A FET current source biases the OP37 into class-A operation. Because of the low voltage from the I/V converter, the op-amp is run at a very high gain (30dB). This op-amp is the only active device between the DAC and analog output; only one gain stage is used, with passive de-emphasis and a passive first-order low-pass filter. The amount of circuitry after the DAC is minimal, owing both to the passive I/V converter, low-pass filter, de-emphasis, and single gain stage/output driver.A dual-channel relay shunts the audio output to ground when the unit isnt locked to an incoming digital signal or when the unit is turned off. Note that the front-panel on/off switch merely activates the shunting relays and turns off the front-panel LEDs; all other circuitry remains fully powered. This ensures that the unit will sound its best without its owner having to wait for warm-up.Build quality is far better than what one would expect from a $499 digital processor. The chassis is nicely made, with countersunk screws, thick metalwork, and a ¼-thick front panel.Listening The Digital Link II provided excellent sound (footnote 1). Although I didnt feel it equaled the California Audio Labs Sigma or Sumo Theorem, it was nevertheless impressive for its price.In perspective, the Digital Link IIs sound was very similar to that of other PS Audio processors: slightly forward in the mids, less than impressive soundstage depth, and a full-bodied low-frequency presentation. Starting with the bass, the Digital Link fell between the Sigmas fatness and the Theorems lean, tight rendering. There was a nice sense of weight to the bass, with fairly good pitch definition. Although not as fast and articulate as the Theorems, the Digital Links bass was rounder and fuller, making the entire presentation warmer.The Digital Link IIs soundstaging was better than the FortéDAC 50s, but not up to the level heard from the Sigma and (especially) the Theorem. There was a slight opacity and congestion to the presentation compared with the Theorem. The impression of individual instruments hanging in space, a sense of air and bloom, and clarity were all good considering the $500 price, but in absolute terms were only fair. The Digital Link II put a thin veil between me and the music, slightly reducing the level of musical involvement. On Robert Lucass Usin Man Blues (AudioQuest AQ-CD1001), the Digital Link II lacked some degree of the transparency, resolution, and air heard from the Theorem, reducing the palpability of the images.One area in which the Digital Link II excelled was its treble presentation, where it was smoother than the Theorem, and even the Sigma. This treble smoothness had its price, however: a slight obscuring of detail. The upper octaves lacked a sense of hearing everything that was going on. Going back to the Theorem revealed that the Digital Link presented less information to the listener than the Theorem. There was, however, a purity and lack of grain in the treble, though not to the same extent heard from the Theorem. To its credit, the Digital Link didnt affront the ears with a hashy, metallic treble. Long listening sessions without fatigue were possible with the Digital Link II. Moreover, the Link had a greater warmth than the Theorem, particularly in the mids.In summary, I would rank the Digital Link II behind the Theorem and Sigma, but ahead of the DAC 50.
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