Digital musical instruments offer countless opportunities for musical expression by allowing artists to produce sound without the physical constraints of analog instruments. By breaking the intuitive link between gestures and sound they may hinder the audience experience, however, making the musician's contribution and expressiveness difficult to discern. To cope with this issue without altering the instruments, researchers and artists have designed techniques to augment their performances with additional information, through audio, haptic, or visual modalities. These techniques have, however, only been designed to offer a fixed level of information, without taking into account the variety of spectators' expertise and preferences. In this article, we introduce the concept of controllable levels of details (LODs) for visual augmentation. We investigate their design, implementation, and effect on objective and subjective aspects of audience experience. We conduct a controlled experiment with 18 participants, including novices and experts in electronic music. Our results expose the subjective nature of expertise and its biases. We analyze quantitative and qualitative data to reveal contrasts in the impact of LODs on experience and comprehension for experts and novices. Finally, we highlight the diversity of usage of LODs in visual augmentation by spectators and propose a new role on stage, the augmenter.