Hannes Rühlmann, also known by aliases Cas and Herr Rühlmann, is a renowned German DJ and producer celebrated for the DJ's mastery of the Acid genre within the electronic music scene. Frequently performing in Berlin, the artist has established a strong presence in the city's vibrant underground club culture. Known for delivering immersive sets that blend classic Acid influences with modern techno elements, Rühlmann has captivated audiences at prominent venues across the city.

Throughout a dynamic career, the DJ has shared lineups with notable artists such as Elias Doré, Uferkind, and Paradox Effects, solidifying a reputation for high-quality live performances. Rühlmann's sets are characterized by their energetic rhythms, hypnotic basslines, and precise mixing, which have made the DJ a sought-after act in Berlin’s electronic music community. As a versatile producer, Rühlmann has contributed to the Acid subgenre with releases that resonate within Berlin’s underground clubs and beyond.

The DJ’s performances often feature in key electronic music festivals, further showcasing the DJ's influence and expertise in the scene. the DJ's collaborations and shared performances highlight a dedicated focus on Acid, techno, and raw electronic sounds, resonating with both local and international crowds. Hannes Rühlmann’s career reflects a deep connection to Berlin’s electronic music roots, and the DJ's contributions continue to shape the city’s reputation as a hub for innovative Acid and techno music. With a reputation built on authentic, high-energy sets, the DJ remains a prominent figure in Germany’s thriving electronic music landscape.