HomePod (1st Gen) Harsh Treble and Tinny Sound on OS 27.0: Issue Persists Since OS 26 Update

how Apple prioritised audio quality when the HomePod was launched in 2018

I recently updated my stereo pair of 1st-generation HomePods to OS 27.0, holding out hope that Apple would finally fix the broken audio balance introduced back in OS 26. Unfortunately, nothing has changed and sound quality remains severely compromised. After listening closely, I realized the real culprit isn't simply a lack of bass—it's an aggressive, over-boosted treble profile. The DSP is pushing high frequencies so hard that they completely drown out and mask the rich mid-range and deep lows that originally made this speaker sound so incredible. This software tuning hits the 1st Gen hardware particularly hard because of its physical design: it features an array of 7 horn-loaded tweeters compared to the 5 found in the 2nd Gen model. Running an EQ curve that heavily cranks the high end through 7 physical tweeters creates a harsh, tinny, and metallic sound profile that becomes almost unlistenable, especially at low to moderate volume levels. To rule out any local configuration glitches or corrupted update files, I performed a full factory reset, removed both units from the Home app, and set them up again from scratch, but the issue persists. Toggling "Reduce Bass" does nothing, as there is currently no control to tame the runaway highs, and Apple hasn't introduced any new audio settings or legacy tuning toggles in OS 27.0 either. Has anyone else with OG HomePods on OS 27.0 noticed this heavy treble bias carrying over from OS 26? Is there any known workaround—perhaps through Apple TV audio settings—to bring down those harsh highs and restore the warm, balanced sound profile we originally paid for? I have already submitted detailed technical feedback directly through Apple's feedback channel, but I would love to hear if the community has found any temporary fixes.