The playing audio without the cable with AsimCDFS I'm quite sure just renders it down to Paula audio so it probably sounds bad compared to CD quality. This has been a feature on Wintel machines for a long time (and apparently some Amiga CD player programs) it just sends the CDDA over the IDE or SCSI bus, but since it's digital it has to go through Paula to make it out to the speakers.
The resistor method is kind of a pain, as the second resistor is on the bottom of the motherboard so it means complete disassembly, but if that's not a big deal then it's simple enough to do.
All that being said the Prisma should support this feature. It is to me a minor scandal that such a simple feature doesn't work out of the box. Maybe the wiki should be updated under the -CDDA header (Yes it's there, it doesn't do anything currently).
With the four connectors on the breakout, maybe one of them is a secondary input and the CDDA could be connected that way?
Back to the years old discussion on this, I understand *It's not a sound card, just a multiformat decoder* since WAV is one of the formats it supports, why couldn't AHI be adapted to send WAV encoded audio to it?