Second Reality was art indeed, but the GUS didn't make all that much difference for it. The soundtrack didn't have higher rate samples for the GUS's memory to hold or more channels for it to mix. Later demos and games did use these capabilities, but for Second Reality, the GUS sounded just about the same as a 16-bit Sound Blaster.
I seem to remember to have watched a recent comparison on YT between Second Reality using SB vs GUS, and I did appreciate an audible improvement with the latter, but it may have been a placebo -- I admit you may be right, as sources seem to confirm that the track used 8 channels that minimised if not outright eliminated synthesis differences. I am not an audiophile or audio engineer by any stretch so more informed people will have to chime in here, but what I had going for me then was the fact I never had a Sound Blaster to compare with directly. I think the fact my card died mere months into my purchase, kind of prevented me from forming a more objective opinion on the quality difference between it and SB.
On a system of that era, some scenes look far smoother with the GUS than SB16. With the GUS running, the CPU could focus on graphics because the audio was offloaded to the GUS. This was particularly true of the 3d flight scene.