The visuals are not perfect, but the voice is impressively feminine.
Here's the singer performing Mariah Carey's "Vision Of Love."
This is a performance as Kichka Bodurova:
Youtube has recent videos of performances as Britney Spears and Madonna. I'll keep my eye out for more as Stefan has performed a female artist in 4 of the 5 weeks to-date.
This is from Stefan's Instagram: