Dialogic feedback demands an active role by lecturers and students to become effective. However, sometimes students do not engage with the feedback received. The use of technology and different channels to provide feedback (using audio and video feedback) in online learning environments could contribute to make students more active with the feedback and improve its effectiveness. The aim of this article is to investigate the use of different feedback channels (text, audio or video) and contrast their impact on academic achievement, as well as to analyse whether the feedback channel influences students' perception of feedback in terms of their preferences. A quasi-experimental study was designed, whereby students received feedback both after they had drawn up the first draft of a written assignment and upon its completion. The results suggest that the channel through which feedback is provided does not have a bearing on performance. However, the study does identify significant differences between the quality of the first draft and that of their final submission. With regard to preferences, students preferred the video channel over the audio or written channels. In addition, they perceived video as the channel that is most conducive to greater interaction and dialogue between lecturers and students, and that also produces the greatest sense of closeness. The results obtained are discussed in light of their importance in an online environment.