Berkeley Audio Design’s Alpha DAC Reference broke new ground in digital-audio sound quality when it was introduced two years ago. But Berkeley didn’t sit on its laurels and regard the problem of digital-to-analog conversion as solved. Rather, the Alpha Reference’s unprecedented technical and sonic performance provided a platform for discovering previously unseen techniques for improving sound quality. Designer Michael “Pflash” Pflaumer spent nearly two years researching these techniques to create the new Series 2.
The Series 2 looks and operates identically to its progenitor. (You can find a full description of the Alpha DAC Reference in my review in Issue 246, or at theabsolutesound.com.) To summarize the salient features, the Alpha Reference will decode all PCM resolutions up to 192/24, has balanced outputs, sports a digital-domain volume control for driving a power amplifier directly, and offers selectable digital filters. The Alpha Reference is designed for all-out performance. That means no DSD decoding and no USB input. To accommodate USB sources you’ll need Berkeley’s Alpha USB ($1895), which converts USB to AES/EBU or SPDIF. This $1895 box is, by a wide margin, the state of the art in USB conversion. Berkeley contends that including the USB input in the same chassis as the D/A conversion circuitry degrades the sound. If you want to play DSD files you’ll need to convert those files to PCM in a computer. The lack of a USB input and DSD decoding speaks volumes about Berkeley’s ethos of no sonic compromises. I’m sure that it has lost some potential customers by omitting both, but it’s not in Berkeley’s DNA to add features that degrade sound quality.
The original Alpha DAC Reference was priced at $16,000; the Series 2 is $19,500. Owners of the original can upgrade for the $3500 difference. (Contact your dealer or Berkeley Audio Design for details.) Note that Berkeley Audio Design is an MQA licensee, and will offer a software update to the Alpha Reference and Alpha Reference Series 2 later this year. The units need not be returned to the factory for the MQA upgrade.
Berkeley is characteristically guarded when describing the Series 2’s technical innovations. The company did, however, suggest that the updates include optimized filters and improvements to the analog stage. It’s worth mentioning that Berkeley takes a different approach to filtering than do other DAC manufacturers. In the Alpha DAC ($4995) and the Alpha DAC Reference, the digital and analog filters are designed essentially as a single cascaded system, with a custom digital filter running on a DSP chip followed by a hand-tuned analog filter.
I was skeptical that the Series 2 could offer a significant sonic upgrade considering the performance of the original. How much room was left for improvement? A lot, it turns out. With the original and the Series 2 in my rack fed from the same source (an Aurender W20 and Berkeley Alpha USB USB-to-SPDIF converter) for side-to-side comparisons, it didn’t take long to hear the startling advances wrought by the Series 2. In fact, I’m so familiar with the sound of the Alpha Reference DAC, and the Series 2 is so much better, that the differences were readily apparent without comparisons.
The first piece of music I played was “You’re Driving Me Crazy” by the Dick Hyman All Stars on the Reference Recording HRx sampler (at 176.4kHz/24-bit). This amazing Keith Johnson recording is exquisitely revealing of DAC quality, from timbral realism, to dynamic expression, to low-level detail, to spatial dimensionality. Even in the short piano introduction, before the band joins in, I could immediately hear the Series 2’s improvement in liquidity and dynamic agility. The piano reproduced by the Series 2 was smoother and less glassy, and the transient attacks of hammers hitting strings were reproduced with greater alacrity. I wouldn’t have thought it until hearing the Series 2, but the original Alpha DAC Reference has a hint of hardness and glare in the upper midrange. By contrast, the Series 2 has a gentle, flowing ease that creates an instant sense of relaxing into the music—a quality that comes so easily to LP, incidentally. This improvement reminded me of the difference between the Magico Q7 and the Mk.II version of that speaker. The Mk.II sounded less bright and forward, but the two speakers had identical frequency responses. The difference with the Q7 Mk.II, and now with the Alpha Reference Series 2, is a reduction in artifacts that are perceived as brightness, glare, and forwardness. Sig-nificantly, this smoothness doesn’t come at the expense of darkened tonal color, a reduction in transparency, loss of treble detail, or a diminution of the impression of air riding above the top octave. Rather, the upper midrange and treble through the Series 2 are full of light and verve, with a full measure of upper-harmonic brilliance and extension despite the apparent lack of brightness.
I’ve previously contended that there’s not a linear relationship between the objective change in a reproduced sound and the musical significance of that change. That is, a “small” change in the signal can have a profound effect on the listening experience. Similarly, a fairly large objective change can have a minimal effect on musical engagement. It depends entirely on the nature of the change. The Series 2’s reduction in hardness and glare, and concomitant increase in ease, liquidity, and timbral purity, is one of those differences that engenders a far greater musical in-volvement than the sonic difference would suggest. The powerful combination of fewer artifacts and more musical information puts the brain in a state of musical receptivity. Consequently, you need more than a cursory A/B comparison to fully appreciate the consequences of the Series 2’s sonic advances. The Series 2’s relaxed ease sneaks up on you during a listening session as you find yourself more deeply engaged in the musical expression. The Series 2’s sound is self-effacing, not calling attention to itself but rather getting out of the way of the performance.