Traditionally, most multimedia content has been developed to stimulate two of the human senses, i.e., sight and hearing. Due to recent technological advancements, however, innovative services have been developed that provide more realistic, immersive, and engaging experiences to the audience. Omnidirectional (i.e., 360-degree) video, for instance, is becoming increasingly popular. It allows the viewer to navigate the full 360-degree view of a scene from a specific point. In particular, when consumed through head-mounted displays, 360-degree videos provide increased immersion and sense of presence. The use of multi-sensory effects -e.g., wind, vibration, and scent- has also been explored by recent work, which allows an improved experience by stimulating other users' senses through sensory effects that go beyond the audiovisual content. Understanding how these additional multi-sensory effects affect the users' perceived quality of experience (QoE) in 360-degree, however, is still an open research problem at large. As a step to better understand the QoE of immersive sensory experiences, this paper presents a testbed and discusses a user-focused study on a scenario in which the user is immersed in the 360-degree video content and is stimulated through additional sensory effects. Quantitative results indicated that the sensorial effects can considerably increase the sense of presence of 360-degree videos. Qualitative results provided us with a better view of the limitations of current technologies and interesting insights such as the users' sense of surprise.