High-rez music is the most exciting audio development to come along in years, and I’ve written quite a bit about it. But I’ve received enough questions concerning high-rez that I felt it was time to devote a column to the subject. What follows is a primer that touches on the basics of high-rez music: what it is, how to get it, and how to play it.
High-rez music refers to audio files that contain more information than the Red Book CD format, which samples audio at a 44.1-kHz rate with 16-bit resolution. High-rez music, in contrast, is typically sampled at a 96-kHz rate with 24-bit resolution. (Though there are some “ultra-high-rez” 192/24 releases that are captured with an even higher 192-kHz sampling rate. Well, hello, Mr. Neil Young....) And unlike the music found at the iTunes store, which is packaged for download using a lossy encoding format called AAC, high-rez music downloads typically use a lossless compression format called FLAC that doesn’t toss any information out in the interest of saving hard-drive space. The result is that high-rez music has a greater sense of depth, with air around individual instruments, more nuanced vocals, and, depending on the production, a better sense of the environment where the recording was made.
Let’s put high-rez file size into perspective. A typical 3-minute iTunes song download takes up a little over 6 MB of space. A high-rez 96/24 download of that same song will take up around 65 MB. A 192/24 file, meanwhile, may require 133 MB for a single song. Thus, high-rez albums typically take up a gigabyte or more of space — not really a problem in this cheap ’n’ capacious hard-drive era.
High-rez audio made a brief go at the mass market a few years ago in the form of Super Audio CD (SACD) and DVD-Audio discs. While there are still discs available in both formats, new releases have slowed to a trickle. Another way to access high-rez audio, and to find the largest selection of titles, is to download them from HDtracks.com. HDtracks offers a free five-track sampler, which is a great way to experience high-rez music and also ensure that your equipment supports playback of high-rez files. Two additional sites to check out are itrax.com and the Bowers & Wilkins Society of Sound.
Many music streamers and recent-model A/V receivers can handle high-rez FLAC files, so if you own one of these, you should be all set. Simply connect a USB drive containing the fi les to your equipment, sit back, and enjoy. Unfortunately, just looking over your hardware’s specs won’t necessarily tell you if it handles high-rez. For example, a NAD C446 music streamer that I recently reviewed had 192/24-capable DACs, but wouldn’t play high-rez files in any format. My Marantz AV7005 receiver also has 192/24 DACs, but playback on it is limited to 96/24 files, not 192/24 ones.
On the software side, many people use WMP or iTunes as their network music server by simply setting up a shared “My Music” (WMP) or iTunes Library folder. But neither WMP nor iTunes supports FLAC, so files in that format simply won’t appear when you attempt to stream them. The solution is to have a separate program running on your computer that acts as the server. I use JRiver Media Center (jriver.com) on my PC, which offers a ton of features, including file conversion, but there are others like Twonky (compatible with Macs) and Media Monkey. When one of these server programs is running, high-rez files will appear in your hardware’s onscreen GUI or front-panel display, and then you can stream them just like any other song. I’ve found that 96/24 files work fairly well when streamed via Wi-Fi, but 192/24 files tend to sound choppy and should ideally be streamed over a hardwired LAN.
The big question: Is high-rez music really worth it? In my experience, the answer is yes. It sounds better and is far less fatiguing to listen to at high volumes. Download the HDtracks.com free sampler and experience the revolution for yourself.
I have found that WD TV Live (at least the current version) truly supports 192/24 files. I ripped some of my DVD-Audio discs to hi-res WAV, and have confirmed that it outputs at that resolution to my Onkyo receiver. Of course, with WAV you need no transcoding. I had a Boxee (which claimed to support hi-res), but it never played back my hi-res files without down-ressing them; the highest sample rate I ever confirmed was 48 KHz. Bottom line, WD TV Live is an inexpensive way to get hi-res audio files to your A/V system and I would propose hooking a hard drive directly to it via USB. Obviously, WD TV Live does a lot of other things that are more prominently touted, so this ability to play hi-res files is icing on the cake. Much better than Boxee in my opinion.
A few years ago, E. Brad Meyer and David R. Moran conducted a controlled listening comparison between "high-resolution" two-channel DVD-Audio or SACD music recordings and 44.1-kHz/16-bit versions of the same. They found that listeners could not tell the difference. (Members of the Audio Engineering Society can read a full report in Vol. 55, No.9, of the AES Journal, from 2007.) This correlates with my own less formal experiences comparing a live feed in a recording studio through various A/D/A chains (44.1/16, 48/16, 96/20, and SACD-type DSD) and in the listening room of an audiophile record label feeding 96/24 recordings through a sampling rate converter that enabled us to vary the sampling rate and bit depth at will. Meyer and Moran did note that DVD-A and SACD releases did often sound better than their CD versions, sometimes much better, but this seemed to be a consequence of differences in mixing and mastering rather than anything technical. Running those recordings through a 44.1-kHz/16-bit A/D/A chain resulted in the same sound quality as the original. So if the "hi-res" files sound better, it's not because they're "hi-res." This is what one would (or should) expect, based on what increased sampling rates and bit depths afford in terms of audio performance. Pushing the upper range of the frequency response beyond 22 kHz or the dynamic range beyond 98 dB doesn't buy you anything in perceived sound quality.
Good points, and I think I've seen bits of that research before. The users listened to headphones and had to go through some sort of "training." Anyhow, the thing that matters to me most is the surround sound that often comes hand-in-hand with "hi-res" recordings, especially in the SACD and DVD-Audio world. There is no denying that listening to a quality Bluray recording of Beethoven's 5th (using lossless DTS-HD Master Audio) in surround is a different world than that same recording in stereo. It is night and day. I do agree that good CD recordings are indistinguishable from stereo DVD-Audio and SACD (quality of the recording, not quality of the format); it's the surround that blows me away.