noun
hi-fi equipment
Refers to high-fidelity audio equipment, such as amplifiers, speakers, and turntables, designed for accurate sound reproduction.
彼はリビングにハイファイ装置をそろえている。
He has set up hi-fi equipment in the living room.
オーディオ is a broader term for audio in general, while ハイファイ装置 specifically emphasizes high-fidelity sound reproduction equipment.
From English 'hi-fi' (high fidelity) combined with 装置 (device/equipment).