Virtual auditory space (VAS) stimuli based on outer ear transfer functions became increasingly important in spatial hearing research. However, few studies have investigated the match between responses of auditory neurons to VAS and free field (FF) stimulation. This study validates acoustic spatial receptive fields (SRFs) of 183 individual midbrain units using both VAS and FF stimuli. The 1^st spike latency, which varied systematically across SRFs, was 14.9±8.3 ms in FF, and 15.1±8.3 ms in VAS (mean±SD). Spike count based SRFs measured 0-20 dB above the neural threshold covered on average 44.5±18.0% of the recorded sphere in FF and 45.5±18.7% in VAS. The average deviation of the centroid position of SRFs using FF and VAS stimuli was 7.4° azimuth and 3.3° elevation. The average spike rate remained unchanged. The SRF overlap recorded using FF and VAS stimuli (mean 71.3±12.6%) or repeated FF stimuli (70.2±14.2%) was high and strongly correlated (r=0.96; p<0.05). The SRF match observed with FF and VAS stimuli was not significantly altered over a range of stimulus levels (paired t-test p=0.51; N=6). Randomized VAS barely affected SRF sizes, centroids, or maximum spike count but decreased the average minimum response to 59% compared to sequential stimulation (paired t-test; p=0.05; N=26). SRF recordings in VAS excluding the acoustic distortions of the recording equipment differed from those in VAS incorporating the equipment (paired t-test p=0.01; N=5). In conclusion, neurophysiological recordings demonstrate that individualized VAS stimuli provided a good simulation of a FF environment.