"Easily The Best DAC I've Heard In My System"
PS Audio's DirectStream is one of the most remarkable DACs ever built. It boasts hand-written, discrete conversion that uncovers all the missing information hiding in your digital audio media. CDs, downloads, high-resolution PCM or DSD based media are expertly upsampled in the DirectStream to ten times DSD rate and output as pure analog directly into your amplifier or preamplifier.
Classic PCM-based DACS, including many of today's DACS that can also process DSD, tend to cover up some of the subtle musical details buried deep within digital audio music; a problem inherent in their architecture. DirectStream solves this problem by employing a pure DSD single-bit approach for both PCM as well as DSD media.
"It's easily the best DAC I've heard in my system, making digitally-recorded music sound better than I've ever heard it," reports Vade Foster in the September 2014 issue of The Absolute Sound magazine.
Hear More Than You Ever Imagined from CDs
DirectStream converts everything to DSD, including PCM, before delivering the music to your system. This approach, coupled with careful design, low jitter, and a simple and direct signal path has the benefit of uncovering details buried in the music you may not have realized are even there. CDs come alive with subtle details that were never apparent with your older DAC. CDs sound more like high resolution audio than you ever imagined, closing the gap between higher resolution PCM and DSD copies. No longer do you need to consider replacing your current CD library because once you hear what's truly on your discs, you may not need to consider upgrading to a higher resolution copy at all. Yes, it is that obvious and significant.
A Better Format
DSD is a high sample-rate, single-bit format, while PCM is a lower sample-rate, many-bit format. DSD sample rates are 64 times higher than those used to create CDs, and the output of a DSD stream can be placed through a simple filter to produce pure analog ready to feed your audio system.
PCM, on the other hand, can produce great sounding music, but to do so requires a very complex and technically daunting conversion process to produce something you can play on your system. Sometimes the simplest path is the best sounding one. DSD is a far more analog-like encoding and decoding process than classic PCM. In fact, most modern A/D converters (used to make the recordings) are DSD-based, and that movement is growing. There are millions of PCM based recordings that will be in our libraries for years to come, but with the introduction of DirectStream, you no longer need listen to them with a PCM based processor.
Converting PCM to DSD
Converting PCM to DSD can be an easy exercise using any number of computer software programs. Converting PCM to DSD properly, and in such a way as to reveal missing details in the music, is a serious technical challenge. To handle this properly DirectStream utilizes 66-bit fixed-point FIR filters, eliminates headroom issues common to PCM, flattens noise response in the 20-100 kHz region, uses coefficients optimized for best sound rather than faster processing speed, and optimizes hardware-specific operations not possible in software.
Unlike other processors available today, DirectStream unifies all inputs (PCM or DSD) at 10 x DSD, then uses a true single-bit double-rate DSD core engine. True DSD core engines (compared to the standard multi-bit Sigma-Delta converters followed by random lower quality multibit converters) offer advantages in simplicity, linearity, and in analog-like overload characteristics that avoid PCM's 'hard clipping' potential and a PCM processor's propensity to mask subtle details.
Pure 100% Single-Bit DSD-based D-to-A Converter
Most of today's sophisticated DACs are IC based instruments using off-the-shelf-chips that are Multi-bit Sigma Delta based designs. While these are relatively simple to design and produce, they don't often give the best results sonically. Because they are one-chip systems, compromises are made in their architecture. DirectStream takes both PCM and DSD, upsamples the data, converts it to single-bit DSD, and then outputs pure music regardless of input format for the data.
Purely Passive Output Stage
Most modern DACs use some form of active tube or solid state output stage to amplify, filter, and drive the DACs output. DirectStream takes a different approach: passive. High speed 'class A' video amplifiers are used as the final switch for the single-bit, double DSD output of DirectStream, feeding a high performance passive audio output transformer. The transformer is specially designed to act as both the galvanic isolation between the DAC and the outside world as well as the primary low pass filter required to present a ow distortion, low noise output signal.
Resolution-Perfect Volume and Balance Controls
A 100% bit-perfect volume and balance control is built into DirectStream, enabling you to control the output level when feeding directly into a power amplifier or preamplifier. That the volume control is completely bit-perfect means there is no loss of resolution for any volume setting, a feature unique amongst the majority of DACS in the world today. The ability to eliminate the preamplifier in the system without any resolution loss is a major benefit to DirectStream's outstanding musical performance.
Simple, Direct Signal Path with Only One Master Clock
Typical high-end DAC designs use more than one master clock, resulting in synchronization problems. DirectStream obviates the problem by basing the entire design on one master clock of extraordinary high quality. Used is a low phase noise, low jitter clock designed for DirectStream by Crystek. Using this advanced approach, the need for synchronization is eliminated, and jitter levels are reduced.
Asynchronous High-Speed USB
DirectStream can match up to either a computer or a home network. If a network connection is desired, the optional Network Bridge slides into the rear panel of DirectStream and adds an additional input. You can also connect directly to your computer via USB. DirectStream provides a fully synchronous 24-bit/192 kHz path for USB based audio. Using a good quality USB cable between DirectStream and your computer, like a quiet Mac Mini, provides an instant media server that can be controlled through any number of handheld devices like an iPod, iPhone or Android using a 3d party controller program. Your music can be managed by iTunes, Bit Perfect, Pure Music or Ammara for ease of use.
A handy feature on DirectStream is the polarity (phase) control. This touch screen option (available on the remote as well) allows you to select normal or inverted phase for every input and for every performance. Sources and music have no standard for absolute polarity, a fact easily demonstrated by switching polarities on the fly as the music plays. Many audiophiles mark their discs 'in-phase' or 'out-of-phase' and are very careful to select the proper phase before playing each disc. Some CD players and sources themselves invert phase so that a disc you believe is inverted actually is correct played on a specific device and incorrect on yet another.
To fix this problem you can assign each input on DirectStream to switch to the proper polarity when you activate that input. Touching this control is the same thing as reversing the loudspeaker connections of both loudspeakers (+ to -) at either the amplifier or speakers. All live acoustic music is in absolute phase, but some recordings may accidentally be made inverted and should sound more realistic and pleasant when you correct their phase with the switch.
Play Directly into Your Power Amplifier or Preamplifier
DirectStream offers the ability to play directly into either your preamplifier or power amplifier through either its balanced or single ended outputs. You can select the optimum gain setting through DirectStream's setup menu to match your amplifier and loudspeaker's sensitivity. If you choose to go through a preamplifier, it's easy to set DirectStream at maximum level (or any level you wish) to match the preamp's gain. But should you choose to eliminate the extra electronics of the preamplifier, DirectStream is more than capable of driving the power amplifier directly. DirectStream's unique zero-loss volume control maintains full resolution bit-perfect performance at any volume setting from the lowest to the highest levels.
Order With or Without Network Bridge
If you would like to add the DirectStream to your network, order it with the optional Network Bridge. The Bridge slides into the rear panel of DirectStream and adds an Ethernet port for a network connection.
"It's easily the best DAC I've heard in my system, making digitally-recorded music sound better than I've ever heard it."
Vade Foster, The Absolute Sound magazine, September 2014
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