After reading https://vintageapple.org/inside_r/pdf/Sound_1994.pdf some more, I found that I can hit TVect breakpoints at SndDoCommand and SndDoImmediate when I run an application that plays sound (Spin Doctor, for instance).  However, I can't single-step through what happens to try to figure out which sound output component is being used.  See the attached MacsBug screenshot -- I end up stuck with a bus error.  If I trace over some of the calls, I can go farther, but I still end up stuck eventually before I make it into a sound output component.

Any ideas what to do here?  Is this as a result of debugging in ROM, and if so, how do I skip over that?