The first time I heard a CD player in my own system was in 1983, the first year of the format's introduction in the West. CD players were generally hard to come by, but I had a friend who worked for Sony, and he came over with his new toy: Sony's next-to-top-of-the-line CD player. (I think it was a CDP-501.) We connected it to my system—at the time, Quad ESLs driven by a Luxman tube amplifier, with a Linn turntable—and listened to some Sony demo CDs.
My friend was delighted with the results. "There's no noise! No clicks, no pops, no rumble!" I had to agree—the lack of noise was impressive. As for the music—well, less so. The sound was bright and harsh, especially massed strings. Piano was better, crisp and dynamic, but voices had more of an edge. I didn't want to spoil his enjoyment, but I wasn't convinced. However, I was intrigued, and determined to find out if CDs could be made to sound better.
So began a long journey. In the more than three decades since, I've owned CD players and DACs made by Arcam, Audio Alchemy, Ayre Acoustics, Mission, Perpetual Technologies, Philips, PS Audio, and Sony. (I don't stream or download.) What encouraged me was that while the Compact Disc itself is a closed system with 16-bit resolution and a 44.1kHz sampling rate, the sound quality of CD playback continued to improve. For me, the greatest improvement came with PS Audio's PerfectWave transport and PerfectWave DirectStream DAC. The combination sounded really good right off the bat, with upgrades of the DAC's firmware (or, as PS Audio calls it, Operating System) producing further improvements.
Can you improve on perfection?
By perfection I don't mean Perfect Sound Forever, Philips and Sony's much-ridiculed claim for the Compact Disc, but PS Audio's name for their first transport: the PerfectWave Transport (PWT). The PWT used what PS Audio called the Digital Lens—a massive RAM buffer that isolates the digital data from the optical drive and laser mechanism, sending the buffered output with a low-jitter clock to the DAC. It's then up to the DAC to turn the resulting bitstream into music. Sounds good—and it did—but can you improve on perfection?
In fact, according to PS Audio's Paul McGowan and Bob Stadtherr—respectively the company's CEO and the chief engineer in charge of the DirectStream Memory Player (DMP) project—the PWT was so good that they doubted whether significant improvement was even possible. However, it's been eight years since the introduction of the PWT, and, for marketing reasons if nothing else, it was due for an update or replacement. In an interview about the development of the DMP, Stadtherr noted, "it's easy to put new chips in there; it's easy to put new features in; it's easy to use the latest, greatest whatever the manufacturers are coming out with," but that "making it sound better is difficult, because sometimes it's difficult to know what makes it sound better in the first place."
I've owned a PWT for about three years, and though it's had some mechanical problems (among other things, its drawer, once opened, would sometimes close prematurely), I've had no complaints about its sound. During a period when the PWT wasn't working, I pressed into service my Ayre Acoustics CX-7e CD player (using its digital output), and the Ayre—whose computer drive had been replaced, but was generally a fine player—was clearly not as good. So when PS Audio announced that it had a new transport in the works that not only could play CDs with higher sound quality, but SACDs as well (the PWT could play only the CD layer of SACD/CDs), I asked Bill Leebens, PSA's genial director of marketing, to put me on the list. "I know your interests," Leebens said. "I already have you down for a review sample."
Design
The PerfectWave Transport's most distinctive design element was that RAM buffer, which could temporarily store as much as 30 seconds' worth of music—you could eject a disc while it was playing, and the music would continue for that long. So I was surprised to learn that while the new DirectStream Memory Player uses the Digital Lens circuit as a "core technology," it no longer has a big buffer: Eject a disc and the music stops almost immediately. Apparently, while the new Digital Lens includes a buffer, it's only just large enough to stay ahead of the bitstream. The DMP's design takes advantage of advances in semiconductor architecture found in large-scale field-programmable gate arrays (FPGAs), also used in the DirectStream DAC. The PWT's main mechanical component was a computer CD/DVD drive made by LG, which had the advantage of being easily available and replaceable in the field. One of the times my PWT malfunctioned, this drive had to be replaced. Rather than shipping the transport to PS Audio, I bought a replacement LG drive at a computer store, and Wallace Poon, the technician at Toronto Home of Audiophile, a nearby PSA dealer, replaced it in about 30 minutes. After that, the PWT worked well. The DMP is based on an Oppo universal Blu-ray player, and operates more smoothly than the LG, as befits a higher-end product. But the DMP is not just a rebadged Oppo: PS Audio uses only the mechanical drive innards; everything else is their own design and manufacture.
In addition to CDs and SACDs, the DMP can play a vast array of recording formats—some I hadn't heard of—on disc or USB flash drive. The DMP will even play BDs, but has no video output, which PS Audio considers detrimental to sound quality. The setup menus include control of a feature called Pure Audio, which turns the Oppo's video engine on and off. (There is no video output in either case.) The recommended position is for Pure Audio to be enabled, which is now the factory default. However, early samples of the DMP, including mine, were shipped with Pure Audio disabled. My early casual listening to the DMP was with Pure Audio disabled, but I can't say I noticed anything amiss. However, when I found out about Pure Audio and enabled it, the sound indeed became more clear. All my "serious" listening was with Pure Audio enabled. As far as I can tell, Pure Audio seems to be part of the Blu-ray standard. I've got an audio-only BD, released by Farao, marked "Pure Audio Blu-ray Disc" (with BD logo), with Kent Nagano conducting Bruckner's Symphonies 4, 7, and 8—four hours of music on a single BD in 24/96 LPCM (two-channel) and 24/96 DTS-HD MA (5.0 multichannel).
A major feature that distinguishes the DMP from the PWT is the former's ability to play the DSD layer on SACDs. As mandated by Sony, the DSD bitstream on an SACD layer is encrypted, to prevent illegal copying; to allow the DSD bitstream to be sent to the DAC, PS Audio developed a proprietary handshake protocol between the DMP and their DirectStream DACs, using the I2S interface implemented with HDMI connections. This keeps both Sony and PSA happy: the handshake protocol prevents copyright violations, and gives PSA DACs access to SACD's DSD bitstream. If a DAC other than a DirectStream is used, or if the DMP–DirectStream connection is not made with I2S, the playback will be of the PCM-CD layer.
Staying up to date with the times, the DMP includes a network connection, to download cover art and song titles from PS Audio's GlobalNet server so that the DMP can display this metadata on its touchscreen, and store it on the included SD card. My audio system has no computer or Internet connection, so I didn't use this feature. The DMP also has a front-panel USB port for a flash drive. This I did try, with a 24/44.1 recording of Bélanger & Bisson's Conversations (Camilio CAM2-5022). It worked fine.
By perfection I don't mean Perfect Sound Forever, Philips and Sony's much-ridiculed claim for the Compact Disc, but PS Audio's name for their first transport: the PerfectWave Transport (PWT). The PWT used what PS Audio called the Digital Lens—a massive RAM buffer that isolates the digital data from the optical drive and laser mechanism, sending the buffered output with a low-jitter clock to the DAC. It's then up to the DAC to turn the resulting bitstream into music. Sounds good—and it did—but can you improve on perfection?
In fact, according to PS Audio's Paul McGowan and Bob Stadtherr—respectively the company's CEO and the chief engineer in charge of the DirectStream Memory Player (DMP) project—the PWT was so good that they doubted whether significant improvement was even possible. However, it's been eight years since the introduction of the PWT, and, for marketing reasons if nothing else, it was due for an update or replacement. In an interview about the development of the DMP, Stadtherr noted, "it's easy to put new chips in there; it's easy to put new features in; it's easy to use the latest, greatest whatever the manufacturers are coming out with," but that "making it sound better is difficult, because sometimes it's difficult to know what makes it sound better in the first place."
I've owned a PWT for about three years, and though it's had some mechanical problems (among other things, its drawer, once opened, would sometimes close prematurely), I've had no complaints about its sound. During a period when the PWT wasn't working, I pressed into service my Ayre Acoustics CX-7e CD player (using its digital output), and the Ayre—whose computer drive had been replaced, but was generally a fine player—was clearly not as good. So when PS Audio announced that it had a new transport in the works that not only could play CDs with higher sound quality, but SACDs as well (the PWT could play only the CD layer of SACD/CDs), I asked Bill Leebens, PSA's genial director of marketing, to put me on the list. "I know your interests," Leebens said. "I already have you down for a review sample."
The PerfectWave Transport's most distinctive design element was that RAM buffer, which could temporarily store as much as 30 seconds' worth of music—you could eject a disc while it was playing, and the music would continue for that long. So I was surprised to learn that while the new DirectStream Memory Player uses the Digital Lens circuit as a "core technology," it no longer has a big buffer: Eject a disc and the music stops almost immediately. Apparently, while the new Digital Lens includes a buffer, it's only just large enough to stay ahead of the bitstream. The DMP's design takes advantage of advances in semiconductor architecture found in large-scale field-programmable gate arrays (FPGAs), also used in the DirectStream DAC. The PWT's main mechanical component was a computer CD/DVD drive made by LG, which had the advantage of being easily available and replaceable in the field. One of the times my PWT malfunctioned, this drive had to be replaced. Rather than shipping the transport to PS Audio, I bought a replacement LG drive at a computer store, and Wallace Poon, the technician at Toronto Home of Audiophile, a nearby PSA dealer, replaced it in about 30 minutes. After that, the PWT worked well. The DMP is based on an Oppo universal Blu-ray player, and operates more smoothly than the LG, as befits a higher-end product. But the DMP is not just a rebadged Oppo: PS Audio uses only the mechanical drive innards; everything else is their own design and manufacture.
In addition to CDs and SACDs, the DMP can play a vast array of recording formats—some I hadn't heard of—on disc or USB flash drive. The DMP will even play BDs, but has no video output, which PS Audio considers detrimental to sound quality. The setup menus include control of a feature called Pure Audio, which turns the Oppo's video engine on and off. (There is no video output in either case.) The recommended position is for Pure Audio to be enabled, which is now the factory default. However, early samples of the DMP, including mine, were shipped with Pure Audio disabled. My early casual listening to the DMP was with Pure Audio disabled, but I can't say I noticed anything amiss. However, when I found out about Pure Audio and enabled it, the sound indeed became more clear. All my "serious" listening was with Pure Audio enabled. As far as I can tell, Pure Audio seems to be part of the Blu-ray standard. I've got an audio-only BD, released by Farao, marked "Pure Audio Blu-ray Disc" (with BD logo), with Kent Nagano conducting Bruckner's Symphonies 4, 7, and 8—four hours of music on a single BD in 24/96 LPCM (two-channel) and 24/96 DTS-HD MA (5.0 multichannel).
