A little over a year later and I finally have some positive updates to report...
Spark is now working for me as an ASIO music player with a proper, working playlist.
This is actually an exciting breakthrough for me on a personal project I've had for awhile now. I'll get into those reasons at the bottom of this post.
Here's how it's done:
1. Create a new "project"
2. Expand the playlist window so it fills as much of your screen as is comfortable.
3. Drop your music files into the left-side pane.
4. From there, drag the music files from the left-side pane to the right side pane.
5. That's it! The right-side pane is now your playlist. You can now select songs there and press play. The music will advance from track to track just as a playlist should.
Remember, this is still a music production application that we're repurposing as a music player. So there's some things to bear in mind.
1. When closing a project or quitting the application, beware when it asks you if you'd like to save the music file - click no to all. I'm sure you don't want it making any changes to your music files.
2. I recommend going into preferences and getting rid of the pause - on Playlist tab set Pause Length to 0 seconds
3. Change the Crossfade type to Hard Cut unless you just prefer something different.
4. On "Editor" tab, set drawing options to 2D. Its faster.
5. On "General" tab, set Overview Creation to "Within temp folder" so OVW files aren't littered over your hard drive next to the music files.
To address the import problem I wrote about before; it turns out the name of my music drive was the problem. The name was "Classic Storage". As soon as I renamed to just "Storage", all the import problems went away. Not sure whether this is app-specific or a symptom of OS 9, but apparently the longer name or the space was messing up file references.
If you can bear to deal with it being a little rough around the edges, Spark XL 2.8 actually works really well as a music player. I've been really enjoying listening to music this way.
Spark, unfortunately, has no MP3 support, even though I'd read in places that it does. This is okay for me since most of my music is AIFF anyways.
Given enough time, I'd still like to figure out a way to get PlayerPro 5.8+ to be operational with ASIO - just so there's choices. Even though the feature is there - it just isn't working for me for some reason, and it's not for lack of trying either.
I've tried on both a MDD and a FW800, both on OS 9.2.2. Neither worked. I've tried 5 different sound cards. No dice. I also tried every single version of PlayerPro I could get my hands on, including the ones at SourceForge.
The only thing I can think of trying next is to get a G3 and try it with OS 9.1 or OS 8.6. That probably won't happen soon though.
Anyways, hope this all helps somebody else out.
Again, this article is written for two types of people in mind:
1. If your audio interface ONLY supports ASIO and you'd like to use it for listening to music
2. The computer audiophile community. I've noticed a trend where much of the longtime community acknowledges the value of having the most dedicated source possible with CD transports rising in popularity. Then there's projects like Wtfplay, PI2AES, Volumio, Fidelizer, and music players like Jplay or XXHE. All of these projects attempt to extract "audiophile level" music quality from Windows or Linux and they start by stripping the OS as far as they can get it. But its still never anywhere as lean as Mac OS 9 (except perhaps Wtfplay, which unfortunately is less flexible on the supported audio interfaces)
Meanwhile, Mac OS 9.2.2 uses just 35 MB of RAM, and you can now send your entire playlist via ASIO to AES (or SPDIF, or optical) and out to your DAC.
This is about as dedicated (read unbloated) as computer audio gets, but no one in the "computer audiophile" community is even mentioning Mac OS 9.
Anyways, my ears are totally loving the new setup.
It might even be the best computer source I've ever set up - only time will tell. But it's definitely very, VERY good.
I definitely prefer it to anything on Windows 7 or later, no matter which player, no matter how many cores - or what scheme is used for core assignments, regardless of how stripped the OS is, and regardless of whether the OS is RAM booted or not.
I think for any "computer audiophiles" out there wanting their computer to get as close as possible to a dedicated CD transport, Mac OS 9 certainly deserves a mention.
*forgot to mention my chain:
PowerMac G4 (MDD) > MacOS 9.2.2 > Spark XL 2.8 > ASIO > RME DIGI96/8 PAD > Breakout Cable BO968 > AES > Neutrik AES to BNC Transformer (part no. NADITBNC-FX) > Kopul BNC Male to RCA Male cable > Coaxial Input > Schiit DACs (Modi 3 and/or Bifrost 4490) > Schiit headamps (Magni 3+, Piety, and/or Valhalla 2) > Sennheiser HD 569 or HD 6xx