Some spiritual ashrams release their chants for free as Seva (charitable service).
T-Series has an official Bhakti app where you can stream and, with a subscription, download high-quality MP3s of the most famous renditions used in Tirumala. Download Om Namo Venkatesaya Chanting Mp3
Warning: Be cautious of illegal download sites that may host malware or corrupted files. Below are legal, safe, and high-fidelity sources. Some spiritual ashrams release their chants for free