Hey, sorry to stop by so late to the party to help out, but i figured a way to fix your little sound problem on Rondo of Blood...
Well, the site i got it from has the iso with the rebdook audio built into it, so it works pretty damn awesomely.
I can only hint at the site, for obvious reasons...
Here's the hint...it is a paradise, for emu's...
(Sounds like it could be a gentleman's club or an island off the coast of Costa Rica.)
Once you get it, there will be two game files, an ".iso" and a ".cue".
Put them where you want.
Then, put the Turbografx CD BIOS ".pce" file anywhere you want (if you place it in the "NitroGrafx" folder (wich should be in the root mem), it will auto-locate it after you select it manually the first time).
Next, when you start up the emu, go over to "options", "machine", "select BIOS", so select it.
Go to "file" and "Load CD rom".
For me, it is the top file of the two Rondo of Blood files.
Hope it works out for ya!
(btw, i'm using r4i-sdhc-dual core-(white-"2013" label). It's the best and fastest card i've used so far.)
Have a great day.