PS Audio Yale OS firmware for the DirectStream DAC

Have you ever purchased an audio product only to learn that the manufacturer had released a new, improved, and upgraded version of your new baby only a few short months after you plunked down your hard-earned cash? If you have, I’m sure you might agree that it’s a frustrating (even maddening) experience, to say the least. In an instant, your pride and joy has become ‘last year’s model’, perhaps even obsolete. But when it comes to PS Audio’s critically acclaimed DirectStream DAC (reviewed in issue 125), I’m pleased to say that owners will be spared the ravages of unforeseen ‘early obsolescence’ and here’s why.

The DirectStream DAC is not so much a singular digital-to-analogue converter in the usual audiophile’s sense of the term, but rather a flexible, powerful, FPGA-equipped and DSP-enhanced digital audio decoding platform whose operation and sonic performance are in very real ways governed by the operating system software the device happens to be running at the time. The term ‘platform’ here is deliberate, to convey the idea that the DirectStream DAC’s sonic performance can and does (along with the unit’s operational characteristics) evolve over time as better and more sophisticated operating system software becomes available. Obviously, this ambitious software-driven product evolution schema sounds promising, at least in theory, but do the real world results make good on PS Audio’s promises? The short answer is that they do.

When I reviewed the DirectStream DAC earlier this year, the device arrived with PS Audio’s then current ‘Pikes Peak’ operating system installed. By all accounts, the Pikes Peak-equipped DAC sounded better than did versions equipped with earlier iterations of operating software, but since I hadn’t heard those earlier versions I basically had to accept reports of sonic improvements as an article of faith. In any event, I came away highly impressed by the Pikes Peak-equipped DAC, especially its detailed, gracious, and free-flowing presentation, which reminded me of the sound of high-quality analogue master tapes (minus the tape hiss).

Lately, however, PS Audio has released a new DirectStream DAC operating system upgrade named Yale (not after the famous Ivy-league university, but after Colorado’s Mount Yale—which PS notes is one of “the 53 mountain peaks in the state that rise above 14,000 feet.”). In a press release on the new OS, DirectStream DAC designer Ted Smith said, “For Yale, I rewrote about half of the DSP code to take advantage of what we’ve learned about noise and jitter from the FPGA.” According to PS, the new OS also reduces the DirectStream DAC’s already low noise floor by 3dB and fixes a few small operational glitches present with the Pikes Peak OS.

OS upgrades are easy to install: download the OS upgrade package from the PS Audio website, load the package on an SD card, power down the DAC, insert the DS card in the DAC rear panel, re-boot the DAC, and wait for the auto-install process to run its course. The amazing part is that the OS upgrade manages—without altering the hardware in any way—to transform the DAC’s sound.

Specifically, I found that with the Yale OS in place, the DirectStream DAC took a significant leap forward in terms of resolution—especially resolution of very low-level textural and reverberant details, and also became even smoother and more mellifluous in its presentation. As a direct result of these changes the DAC sounded noticeably more ‘continuous’ (to borrow a term coined by the late, great audio journalist Harry Pearson) and more convincingly three-dimensional. Perhaps more importantly, the DAC’s ‘palpability factor’ also went way, way up, meaning that sonic images of instruments and human voices became far more solid and vivid with a kind of breath-taking ‘you-are-there’ realism.

These sorts of substantial improvements in sound quality usually take place through costly and elaborate hardware upgrades. Now, however, PS Audio—along with a handful of other forward-looking manufacturers—has shown us a better kind of upgrade path. In the case of the DirectStream DAC, PS Audio’s formula calls for building and selling a hyper-capable hardware platform whose full sonic capabilities are, arguably, not fully known to the design team at the time of the product’s initial release. Then, over time and as the team gains more insight into what their platform can actually do, successive operating system updates tap more and more of the platform’s sonic potential, giving the product an ‘evergreen’ quality that will not rapidly become obsolete. Well done, PS Audio!

TECHNICAL SPECIFICATIONS

• Type: Operating system upgrade software for the PS Audio DirectStream DAC
• Noise: Noise floor is reduced by 3dB vis-à-vis the ‘Pikes Peak’ OS
• Jitter: Jitter reduced by an unspecified amount vis-à-vis the ‘Pikes Peak’ OS
• Storage/Installation requirements: SDHC memory card (OS upgrade software requires approximately 4.1MB of storage capacity)
• Price: Free of charge to owners of PS Audio DirectStream DACs

Manufacturer Information: PS Audio

URL: www.psaudio.com

Distributor Information: Signature Audio Systems

Tel: +44(0) 7738 007776

URL: www.signaturesystems.co.uk