YMF71x switcher between WSS and SB mixer according to what side was last accessed. WSS mixer has much finer settings than the SB mixer and SETUPSA doesn't actually expose you the real decibel figures. My SETYMF does, you can find it here :
http://www.tmeeco.eu/TKAYBSCRunning an SB game or sound test beforehand will switch to SB mixer values and the Adlib only game will then use those values unless it somehow triggers WSS mode for the sound card which is unlikely.
That reminds me, I don't actually explicity make sure the card is in SB or WSS mixer state in SETYMF when the program exits. I'll have to look into it.