Are there any online dictionaries that supply IPA transcriptions for Cantonese? I know little about Cantonese (for now), but please advise me if I erred in conjecturing that IPA is more precise and helpful than Yale or Jyutping Romanisations.
You might try the 漢語多功能字庫, with traditional Chinese, English interface.

On the top right corner, you can choose the scheme: IPA (number) &amp; IPA(letter).

Have fun. :)