I installed a volume knob on the side of the cabinet to manually adjust the speaker volume and even turn it off. You can also go into the attendant menu and change the volume there if I'm not mistaken. It's been a while since I booted my cabinet with legacy software on it, it has been converted to CPUNXT.
Here are some of the legacy (WMS55x/36x) games available for your platform. There are probably a few more that are not known to me.
Aztec Adventure
Best Things in Life (Life of Luxury 2)
Bit Tipper
Boom
Bottom Line
Cash Crop
Crocodile Cash
Filthy Rich
Hollywood Squares
Hot Toppings
Instant Winner
Jackpot Party
Leprechaun's Gold
Life of Luxury
Love to Win
Money Groove
Money to Burn
Off the Charts
Perfect Game
Ree 'em In
Roll Credits
Something 4 Nothing
Stages of Riches
Swinging in the Green
Toast of the Town
Top Banana
Who Dunnit
Wild Streak
Winning Bid
X Marks the Spot
Yukon Gold.