From mrgoodsound: Music from the computer!

By mrgoodsound

Hello! I apologize for the lack of articles from my end, there has not been enough time to listen to gear let alone write about it. 

Today's article is about a very advanced subject; one that many people on the internet, in forums, think that they have all figured out. Unfortunately, like many things in audio, it's complicated.

I am talking about how to listen to music using a computer as a digital source. Streamers are the latest craze in high-end audio, and manufacturers were quick to launch products which are essentially closed-system computers in fancy cases for obscene prices. More tech savvy users have already figured out how to copy the efficacy of these products for a fraction of the cost using an inexpensive Raspberry Pi mini computer and some specific add-ons. 

The oldest and most successful computer for music playback is the CD player! Its technical weak point is the optical conversion, reading a disc via a laser system and generating an electrical data stream. But besides this, it has many advantages the modern computer does not: a short signal path, absence of interference, construction using fine vintage components designed for audio, a bare minimum of software, etc. 

As much as I like to play CDs, I have the need to listen to rare recordings which were never issued on CD, or have become impossible to obtain on factory discs. As much as the streamer and networked audio fad has taken off, I have other specific requirements which preclude me from such a solution.

For my digital source, I require:

• The ability to stream Tidal, for modern recordings
• The ability to stream web-based content, such as YouTube, NML, internet radio, sites containing archived rips of 78 rpm records
• The ability to view music videos and concert films while listening
• The ability to rip and burn CDs
• The ability to play local files without an internet connection
• The ability to output sound via USB (more on this later)

So basically, I need a regular computer with a monitor, mouse and keyboard. I do not fit into the headless (controlled remotely) streamer crowd but at the same time want the best sound quality possible. What to do?

For the past year, I have been using a modern HP laptop running Windows 10. It has been connected to a USB-to-S/PDIF converter which in turn feeds my DAC. Why a converter? My DAC only has S/PDIF input and the number of ways to get a clean S/PDIF signal out of a computer are very limited. This solution worked OK, but the sound was far from inspiring. I felt for a long time that my digital transport was the weak link in my chain, and I have also felt historically that at least as much attention should be provided to the transport as is to the DAC.

Generally, laptops are not good for audio. They need a switch-mode power supply to charge the battery and all of the components are tightly packed together increasing potential for electronic interference. Generally, Windows is terrible for audio. As an operating system, it already has a reputation for being unnecessarily bloated, and the way it manages the interface between audio hardware such as a USB DAC and the software responsible for audio playback is no exception. There was a strong desire to move to a silent desktop computer using a non-Windows OS.

a simplified view of the Windows audio stack

Shiny new hardware

Luckily, I had an opportunity to purchase an early 2008 Mac Pro from a close friend for a very reasonable sum. This machine had seen service inside a recording studio, alongside a fleet of similar machines used for production and file backup. They specifically used this model of Mac Pro not because they were too cheap to upgrade but because there was no point, the newer machines from Apple had seen serious design flaws and reliability issues due to cost cutting.

I took the machine home along with an original Apple display and installed it in place of my Windows laptop. After an hour of messing around with playback software and settings, I started to listen. I expected results, but what I experienced was transformative. The sound was much improved in terms of dynamics, clarity, intelligibility and timing from both internet and local sources! How can this be?

The answer is a mix of hardware and software. On the hardware side, the 2008 machine is simply something to behold. Aside from an all-metal construction and very thick PCBs, even the quality of capacitors on the motherboard and inside the power supply were more like what you would see in a modern audio component than a computer. I was told the power supply in this particular unit was a special part number from Apple designed for low-noise professional applications. I haven't verified if that's actually true, but it would help. 

OSX playback software

On the software side, Mac OSX is simply very far ahead in terms of audio optimization when compared to Windows. There are no competing APIs such as WASAPI, ASIO, etc. but instead just the Apple-maintained low latency CoreAudio system. There is no myriad of hidden settings and optimizations to make scattered around the operating system, no alternative USB drivers to deploy, everything kind of just works. There is not as great a choice in playback software, but this is fine as I was able to find an honest one relatively quickly. 

I first tried Audirvana, which seems to be the go-to 'audiophile' playback for Mac. Supposedly it bypasses the system audio mixer and performs some other optimizations. Unfortunately, it does not sound very good to my ears. The low end is fairly boosted, leaving not much clarity in the lower mids, and the overall sound presentation is very 'hi-fi'. I can see how it would impress others, but I quickly moved on.

I next tried SoundByte, which is actually a sound clip carting software made for DJs and radio operators. You load up sound files and then have a bunch of options to play them back, fade them into each other, etc. Of course I didn't use any of these tools and simply create a playlist of the files I want. For whatever reason, SoundByte is the most honest player: all frequencies have the correct level, the sound gains in depth and more subtle intonations are revealed. 

Older is better?

I should've probably stopped here, already extremely satisfied with the quality of playback I was getting along with the absolute convenience of a computer connected to the internet, but curiosity got the better of me. I read more than once that older versions of Mac OSX sound better, and I decided to try one. My machine came pre-loaded with OSX 10.11 El Capitan. This is basically the oldest version of OSX (2015) which still has wide compatibility with modern software such as web browsers and media players. It ran reasonably well on my 2008 Mac, but there was still an occasional slowdown and freeze.

I decided to go way back and settled on OSX 10.6 Snow Leopard (2009), for several reasons. First, it would've been a period correct OS to be running on my particular machine. Second, it was the first release of OSX where Apple abandoned PowerPC compatibility and thus had a general reputation for being stable and lightweight. Third, I read a few anecdotal impressions praising the sound of this release over subsequent OSX versions. 

Since the Mac Pro has multiple hot-swappable hard drive bays, it was very easy to install an alternative version of OSX without interrupting my current installation. Two hours later and I had a fresh install of Snow Leopard, ready to test with music. To my surprise, my USB audio device was detected instantly and playback worked right away without additional configuration. Not yet internet connected and not wanting to use iTunes, I simply pressed play on the first file I found through the system default 'Quick Look' media player. 

Well, I was rather stunned at the results. There was another leap in sound quality, perhaps even to the same magnitude of jumping ship from Windows to Mac in the first place. I immediately heard greater articulation, finer detail, less aggressive and glassy sound, better rhythm and timing, and a more correct volume between instruments in the mix. How can this be? I don't really know. All I know is that at this point preconceptions about computers and digital audio should be left at the door, and the only solution for good sound is through tinkering and exploration. I went back to the Windows laptop for a reality check and was disgusted at what I heard, a sound that was simultaneously dull and aggressive. Go figure.

Trouble in paradise

My victory celebration ended when I tried to go online. The old version of Safari that came standard with the installation was simply unusable, it couldn't even load the Apple website. I had to download an old, unsupported build of Google Chrome using another computer and transfer it over. Next, I realized that the TIDAL web player wouldn't work. Well, this was to be expected. Lastly I tried YouTube and while it did play audio just fine, going full screen caused the video to become choppy and lag the entire system. Such is the fate of old operating systems, but at least I can still listen to rare and historical recordings online.

Like Icarus, I ended up flying too close to the sun. My installation disc for Snow Leopard was version 10.6.3, and the version recommended to me by a foreign acquaintance for best sound was 10.6.6. I went to Apple's website, downloaded the appropriate patch, and let it install. Upon rebooting the computer, it just hangs and will not start. I suspect a display driver error as the original video card in the system was replaced with a better one. Oh woe is me, as I became greedy and could not settle for one large jump in sound quality for a day. I will have to erase the drive later and reinstall 10.6.3. Thankfully, I can go back to using my original El Capitan installation at any time just by holding down a key during system restart.

Next steps

The results of these experiments have convinced me the old Macintosh computer is a very suitable digital transport. I would not recommend the Mac Pro, it is very large and rather expensive, but a Mac Mini of a certain vintage is an excellent choice and will fit into an audio rack. In fact, there was a period of time in audiophilia before the popularity of networked audio and streaming that Mac Mini's ruled the roost for music servers. I would not recommend the modern ones however.

For me, I am curious at just how farther this can go. I plan to acquire a PowerMac G4 from 1999 to see how it sounds for playback of local files. I am doubtful it will support my USB device but there are other ways to extract an audio signal from it. If this all sounds quite insane, it probably is, but it's also fun. I got quite a kick out of using an 11 year old operating system to play music, and messing around with software is free. The best advice I can give for computer audio is to dedicate the computer system to the task of playing audio, and ditch Windows entirely.