The Sovtek 7591XYZ is a type of vacuum tube, commonly used in audio amplifiers. Sovtek is a well-known manufacturer of tubes, and the 7591 is a variant of the 7591 family, often used in high-fidelity audio equipment, such as tube amplifiers. The "XYZ" part of the name typically refers to specific variations or batches in the series.

The 7591 is a power tube originally designed for use in 1960s-era audio equipment. It is highly valued for its warm, musical tone, which is a characteristic of tube amplification. The Sovtek 7591XYZ version would maintain this tonal quality, but it may have specific design adjustments that offer better durability or performance in modern equipment.