Pure Music Software (Playback, from TAS 209)

In Issue 202 I concluded my review of the Amarra software program with, “If you want to hear how good a quality Mac-based system can really sound, you have to use Amarra. In the end, it’s that simple.” Time and the latest version of Channel D’s Pure Music software may make me eat those words. Priced at only $129, Pure Music promises to improve not only iTunes’ sonics, but also adds high-resolution capabilities along with a host of other advanced sonic and ergonomic features.

Pure Music is such a powerful program that reading its “User Guide” is a must. I daresay that you will be reading this informative tome more than once. I recommend keeping Pure Music’s User Guide PDF open on your desktop for the first week or so of operation, especially during initial setup. While nothing in Pure Music’s preference panels is completely inscrutable, without the User Guide anyone not familiar with Pure Music’s many options could screw up its settings in a myriad of ways. Don’t say I didn’t warn you.

Pure Features

Like Amarra, Pure Music’s principal function is to bypass iTunes’ signal processing and substitute a more direct and powerful 64-bit processing program. In addition Pure Music offers automatic rate-switching from 44.1/16 all the way up to 192/24, gapless playback of files that have been designated as gapless files, memory play, real-time high-resolution upsampling of CD tracks, a 64-bit internal signal path, dithered volume control, phase inversion, a subwoofer crossover, multichannel support, support for audio processing plug-ins, Core Audio HOG mode playback, high-resolution audio streaming, precision signal metering, reverse play, and more. Some of these features, such as HOG mode and memory play may sound like gibberish to the uninitiated, but these two features alone make Pure Music capable of elevating even a lowly Mac Mini into a formable music delivery device.

I could easily fill many pages with a detailed description of individual preference panes and the various options these panes offer, but you can download the User Guide along with a demo version from Channel D’s Web site.The free demo offers fifteen days of full-featured usage, and I daresay that once you’ve used Pure Music going back to ordinary ol’ iTunes will be tough, unless you’re listening through a Dixie cup and a string.

Although a novice user, the sort of person who feels intimidated by anything labeled “preferences,” can simply download and run Pure Music, to hear its full potential does require optimizing it for your particular system’s capabilities. But even when it is used “plain vanilla” without any system optimization, I could hear differences between iTunes and Pure Music.

Among Pure Music’s “must use” features is memory play. This loads your music file’s stream into an adjustable RAM buffer before it’s sent to your rendering device or DAC. It usually takes a few seconds for the buffer to fill and music to begin playing, but you can select a “Hybrid buffer” setting which will play the first couple of seconds of a track without buffering while the data is loaded into the buffer and then automatically switches to buffered mode once the buffer is filled.

Pure Music’s upsampling capabilities allow it to turn a 44.1/16-bit file into a higher-res file. Among the options are “power of two” upsampling. According to Pure Music’s User Guide, “this operation is more efficient than factored upsampling, and in the case of Red Book CD, 88.2kHz is, all things considered, a better target than 96kHz.” If your DAC will support it, a Red Book CD can be upsampled all the way to 192kHz. With the Weiss DAC 202 I was able to set up Pure Music so it upsampled 44.1/16 files to 192/24 before sending them to the DAC.

Another unique feature of Pure Music is the HOG mode. According to the user guide, “this option reserves the audio device for Pure Music’s exclusive use while Pure Music is running. To use this feature, the audio device selected in Audio MIDI Setup should be set to a different device than the one used by Pure Music, to allow iTunes to fully access an audio device if necessary. Accordingly, by default, HOG Mode cannot be used for the audio device selected in Audio MIDI Setup.” This feature is best used on a dedicated music system. On a full-service computer it means that any time you want to use any program that requires an audio stream it will have to go to an alternative audio device, such as your internal speakers or a second DAC.

My final preferred HOG setup was pretty clever, if I do say so myself: I used the Weiss DAC 202 in FireWire mode for my Pure Music feed and the Empirical Audio Off-Ramp 3 for all other audio tasks. To change from Pure Music to other audio sources I only needed to select the DAC 202’s RCA/SPDIF input.

Pure Music also allows the use of third-party plug-ins, and comes with18 plug-ins already installed and waiting for activation. A plug-in is a small application program that runs within Pure Music. Installed plug-ins include a peak limiter, graphic EQ, high-pass and low-pass filters, compressors, reverb, and shelf filters. My favorite plug-in is the Roger Nichols Digital Inspector, which shows clip incidents, consecutive clips, overall headroom, and master levels in real time for any music file being played through Pure Music. (Digital Inspector isn’t included in Pure Music.) Since each plug-in takes up processor time, Pure Music monitors the total CPU load so that you don’t overload your computer by using too many plug-ins at one time. On my Mac Pro with 12 gigs of memory I was able to run quite a few plug-ins simultaneously. But the best way to use plug-ins is with restraint. You can, if you’re so inclined, use up to 14 plug-ins at the same time, but that would be a wee bit excessive.

With the right hardware you can even have Pure Music handle crossover settings for a multi-amped speaker system. To utilize this feature you will need a multichannel output device such as a Lynx AES-16 or Apogee Ensemble. Each channel can be selected and modified by Pure Music. For a two-way speaker system, channel one could be right tweeter, channel two the right woofer, channel three the left tweeter, and channel four the left woofer. You can choose either 6, 12, 18, or 24dB per octave slopes for both the high pass and low pass. You can also adjust individual levels for each channel, and the delay for each channel, making this a very powerful and flexible way to configure your crossovers.

While earlier versions of Pure Music had some small ergonomic quirks such as reading out “paused” while it was playing, the current version, 1.6.3, proved to be exceedingly well-behaved. The only problem I experienced was with the Wyred4Sound DAC 2. During the silences between cuts I heard low-level crackling. Since this DAC uses its own proprietary driver, I suspect that’s the culprit. I alerted Wyred4Sound of the problem and they added it to their bug-fix list for the next version of the driver.

One ergonomic issue I was glad to see Pure Music doesn’t have is Amarra’s death-grip on the computer’s CD/DVD drive. If you rip a CD via your internal ROM drive while Amarra is running it won’t let you eject the disc. You have to shut down Amarra (which shuts down iTunes) before you can remove the disc from your drive. That gets old pretty fast.

Pure Sonics

How does Pure Music sound? Better than iTunes alone, that’s for sure. Compared to iTunes Pure Music is more dimensional, dynamic, detailed, and involving. ITunes sounds flat, not pitch-wise, but in its overall presentation. It is like going from a 128kbs MP3 file to a 320kbs file. Pure Music delivered substantially more musicality and more information than iTunes did.

I found I got the best sound from Pure Music when I used both memory play and HOG mode. This combination delivered a subtle improvement in both overall soundstage depth and dimensionality. The spaces around and behind individual instruments were better defined. The amount of improvement will vary depending on your particular hardware configuration. Although I heard the improvements through the Wyred4Sound DAC 2, the improvement was more pronounced through the Weiss DAC 202.

Naturally, I compared Pure Music with Amarra. Unfortunately because you must shut down each program and iTunes when you switch from one program to the other, I couldn’t do the kind of direct real-time A/B tests that I usually employ. On the longer, slower, A/B comparisons I couldn’t hear any differences between Pure Music and Amarra. Both were clearly better than iTunes, a fact I could easily ascertain via matched-level instant A/B comparisons.

Given that I found sonic differences between Pure Music and Amarra negligible, and Pure Music costs approximately 25% of Amarra’s price does that make Amarra obsolete? For budget-conscious audiophiles the answer is yes, but for those who are using one of the professional DACs that Amarra supports, Amarra still may be a better option. Also, given Sonic Studio’s rapid rate of innovation, it’s possible that by the time this review sees print Amarra may have seen improvements of its own.

I’m sure many readers would like to know how a Pure Music-enabled Mac system stacks up against a top-flight transport. Sorry, but you won’t find any answers here. To be completely forthright, I don’t listen to CDs through CD players or transports anymore. For me a CD is merely a way to get digital files. When I receive a new CD, I “play” it exactly once, when I add it to my digital library. Then it goes onto a shelf to collect dust. Transports are as useful in my world as a capo on a mandolin.

Pure Pleasure

Pure Music is a great piece of software at a price that even a flea-market-scrounging audiophile hobbyist can afford. Combine Pure Music with any recent Mac computer and you have a front end that will play back any digital file (except FLAC) from lowly MP3s up to 192/24 high-resolution with ease. Mate this front end with a top-flight DAC such as the Weiss DAC 202 and you have a digital playback system that will catapult you to the forefront of the new computer-playback revolution. Dare I say it? If you want to hear how good a quality Mac-based system can really sound, you have to use Pure Music, at least for now.

SPECS & PRICING

Hardware Platform: Apple Macintosh OS 10.4, 10.5, 10.6 with iTunes
Price: $129 (free 15-day trial with all features available)

CHANNEL D SOFTWARE
(609) 393-3600 (live support available 9-5 EST)
channld.com

Associated Equipment
Source Devices: MacPro model 1.1 Intel Xeon 2.66 GHz computer with 12 GB of memory with OS 10.6.4, running iTunes 10.0.1 and Amarra 1.2 music playing software
DACS: Weiss DAC 202, Empirical Audio Off-Ramp 3
Preamps: none
Amplifiers: Bel Canto S-300 stereo amplifier, Edge Electronics AV-6, Accuphase P-300 power amplifier
Speakers: ATC SCM7s, Paradigm S1s, Aerial Acoustics 5Bs, Role Audio Kayaks, Earthquake Supernova mk IV 10 subwoofer
Cables and Accessories: Locus Design Polestar USB cable, Locus Design Nucleus USB cable, PS Audio Quintet, AudioQuest CV 4.2 speaker cable, AudioQuest Colorado interconnect, Empirical Audio Coax digital cable.