there's a lot of equipment involved in running the sound on these things.
parts to note: main PCB cage (the data for the sound comes from here), the sound board (this processes the sound), and the amplifier (kind of self explanatory I think).
hunt down the sound board first. there should be 2 sets of connectors going to it, they have like white-ish wiring, that comes off the back of the main PCB cage. ensure first that those are connected properly. if this doesn't get it, move on to the next step: there are 2 RCA plugs (stereo sound) on the sound board, these go to the audio amplifier, follow those, make sure those are plugged in good and tight. alternatively, you could try running it with these unplugged, and see if you still get the same garbage sound, I guess for fun.
to be safe, if you got replacements laying around I suppose you could replace the RCA cables too.
if all your connections appear to be good and you're still getting garbage sound, I would say your problem is probably in the sound board itself. the ROM chips in it can be susceptible to "chip creep", but I found that a mere pressing down of the roms on these boards can be a bad idea. I don't know which cabinet design you have, but on the sitdowns all kinds of SHIT can build up on the PCBs underneath, and without cleaning the sound board off on one of mine first, I wound up lodging little wood chips in the ROM socket and broke the socket.
grab a toothbrush/paintbrush and make sure all the little shit that may be on the board is cleaned off first. you may have to separate the 2 halves of the sound board to do this if I recall... just make sure they're on a flat surface so you don't bend/break the boards.
(replacements for those sockets aren't overly abundantly available.... unless you're psycho like me and find that in the main PCB cage, on the ROM board, that there's some unused sockets and grab a donor from there.

)
then obviously reconnect everything the way it's supposed to be.
I hope this helps. if it doesn't, then you're gonna have to hunt down a different sound board to try out in there.
another likely scenario is your amp could be bad too, I don't know about Daytona 1, but on Daytona 2 if the speakers are blown they can blow up (like literally put a hole in it) the IC on the amp. run an ohm test across the + and - terminals on your speakers, I forget if they're 4 or 8.
that's all I got.