For AV equipment, CBP applies a 'substantial transformation' test — the country where the product undergoes its most significant manufacturing operation (e.g., final circuit board integration and functional testing) is generally deemed the country of origin. Multi-country supply chains require careful documentation of each production step to support the declared origin, especially where Section 301 tariffs create financial incentives to shift assembly locations.

Combination devices (e.g., a soundbar with a built-in streaming receiver) must be classified by their principal function under GRI 3(b) or 3(c) rules. Misidentifying the primary function can place the product in a heading with a materially different duty rate or Section 301 exposure. Consulting a licensed customs broker before the first shipment is strongly recommended.