Do we have to get ba-wudu even if we reciting or listening Quran online?
There seems to be general agreement that qira’ah (reading/listening to/reciting aloud the Quran) can be done without wudu. The only thing that most agree should not be done without wudu is touching a book of Quran (i.e. a mushaf) (however, the highly respected Shafi`i jurist and hadith scholar al-Hakim al-Nisaburi says that touching a book of Quran without wudu is permissible).
Reading/listening online seems to me to fall under the first category, so I wouldn’t worry about wudu.
Source for first paragraph: Islamweb.net, fatwa #12540.