One of the major challenges in performance space design is to provide a stage enclosure that supports musicians in their ensemble playing. To overcome the limitations of field studies, it is of interest to be able to evaluate musicians' preferences under laboratory conditions. This requires that all musicians hear their own and each other's direct sound as well as the room via real-time convolution. With such a system, musicians can play as an ensemble in many virtual concert halls in a short period of time and evaluate their preferences.Such a setup was designed for a listening experiment. Open headphones were used to auralize the environment while still allowing direct sound to be heard in the experimental room. The experiment was conducted in an anechoic environment to eliminate natural reflections. Latencies as low as 22 ms were achieved, allowing the evaluation of even small chamber music venues. The BRIRs were simulated using the geometric acoustics software RAVEN, taking into account the directivities of the musical instruments as well as head rotations via head tracking. A convincing degree of realism was reported by the participants.