When sourcing high-end sofas, you must prioritize frame construction, typically requiring kiln-dried solid wood or larch to prevent warping. For cushioning, ensure a high-resilience (HR) foam density of at least 35kg/m³-45kg/m³ to prevent sagging over time. If sourcing leather options, verify the use of top-grain bovine leather rather than split leather or bonded leather to ensure durability and a premium tactile experience. Additionally, check for S-spring and high-elastic webbing systems to guarantee long-term structural support.