While Castlevania games are heralded for their ostentatious Soundracks, Castlevania:Harmony of Dissonance is often disregarded as a lower-grade cousin among the bunch.
The reason for this common opinion is that the graphics in CV:HoD were so advanced(for the time and console), that in order to produce them without lag, the development team decided to shut down polyphonic audio(which ran on the CPU) to save processor cycles. Instead, audio was handled through the PCM chip (Added to the GBA as a backwards-compatibility for the Game Boy Color) resulting in low fidelity audio, way too little for Castlevania’s signature symphonies.
If you actually listen beyond this limitation, you’ll find that Soshiro Hokkai and Michiru Yamane did a spectacular job of working within their constraints, creating some truly unique chiptunes in the process.
(Successor of Fate and Chapel of Dissonance are my favourite tracks)