[BUG] Modern sampled sounds garbled on UltiSID

[C64Mat]

Describe the bug
Old SID sampling techniques on old commercial software largely work fine here, with the exception of The Last V8, which weirdly sounds corrupted. Other speech, such as that found in Impossible Mission, Myth, The Ninja Warriors, Exploding Fist all sound just as they did on original hardware (note that you can go into the audio menu and increase the volume of samples specifically, which is great if you're using the 8580 sound emulation).

But whatever techniques modern developers use to create their SID samples, they don't appear to work well on the Ultimate at all. A Pig Quest "Piggy 18" intro speech sounds messy and crunchy. The speech for Planet Golf has the same issue, often being absolutely unintelligible on the course, when it would normally say things like "It's all about gravity". You can barely make it out. The "Let's Golf!" speech before playing a round is garbled and pitch shifted up at least an octave. The "SEGA" speech at the start of Sonic the Hedgehog 2 is messy. None of these issues appear either on original C64s OR software emulators like Vice, where all the speech sounds clear and great.

It's the one mar on another wise excellent product.

Edit: Also noted in some much older titles, like The Last V8 and Apollo 13

To Reproduce
Steps to reproduce the behavior:

1. Load Plenty Golf as an example
2. Select UltiSID as you SID in any config you like
3. Play the game normally, then try hitting the ball out of bounds
4. Samples are unintelligible, despite being clear on real SIDs of emulators.

Expected behavior
For the samples to play cleanly as on other hardware/emulators. There are some big games coming like Impossible Mission III, which features over 30 samples, which may be unplayable on the current official Commodore 64 that 20,000 people have bought. The samples in games like that and Planet Golf and Apollo 13 are integral to the experience.

Applies to

• Hardware type: Commodore 64 Ultimate, community's reports of any UltiSID product
• Firmware Version: Latest (3.14?)

Additional context
There have been multiple topics about this in forums such as Lemon64, and there are already bug reports for it, but they seem to mention specific games, so I've logged this as a catch-all bug report. If anyone wishes to add examples to this list to support possibly looking into it, that would be great!