Got back into town a while ago, and got the chance to give the cable a test:
I ripped the Tori Amos song, "God" (first half-minute or so is great for a quick listening test) into FLAC, and left it on my hard drive. Then I listened to the CD in my Oppo player -- sounded amazing. Then I hooked up the laptop to the receiver using the headphone-to-stereo RCA cable, and listened to the same song -- sounded a little less than amazing.
Through the laptop, there were audio artifacts going on throughout the song, as well as what I can only describe as a faint crackling -- low in volume, but noticeable, especially after listening to the CD in the Oppo. And this could be just my imagination, but the music through the laptop seemed a little constrained somehow. Anyway, this confirms that while the use of this new cable might be acceptable for casual listening, I'll have to find another method for enjoying listening to FLACs. Maybe the Turtle Beach dongle is what I need.
Thanks so much for your help and opinions, everyone!
cheers,
Vij