This entry represents a collaboration between two separate premium audio companies: Astell&Kern (South Korean, founded 2013) and 64 Audio (US, founded 2010). Astell&Kern, based in Seoul, specializes in high-end digital audio players and home audio systems, known for Mastering Quality Sound (MQS) technology. 64 Audio, founded as 1964 Ears by Vitaliy Belonozhko in Portland/Vancouver WA, creates custom and universal in-ear monitors for musicians and audiophiles. Both companies are family-owned businesses focused on premium craftsmanship. Their notable collaboration produced the XIO in-ear monitors, a $3,000 premium product featuring 10 drivers in precision-milled 904L stainless steel housing. Astell&Kern combines precision engineering with artistic sensibility for portable hi-res audio, while 64 Audio focuses on proprietary IEM technologies and acoustic design. Together they represent the intersection of premium portable audio players and professional-grade in-ear monitoring solutions, serving global markets with products sold in 90+ countries.