Falcom Sound Team jdk laid out the evolution of Ys music across hardware generations and it's kind of staggering to hear side by side. You get "Feena" as a PC-88 original, then the Ys II version, then the Ys Eternal remake, each one carrying the same melody through completely different sound chips and production values.
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"Tower of the Shadow of Death" hits different depending on which version you're hearing, the raw FM synth original versus the richer Eternal arrangement. "Palace of Salmon" from Ys II still has one of the best bass lines in the entire series.
This is basically a documentary in album form, tracing how Yuzo Koshiro and later Falcom arrangers kept reinventing these compositions. Essential listening for anyone who wants to understand why Ys music became legendary.