10. Can the vacuum tubes in the WARMER R2R be replaced?

Why are they placed inside the device?

1.The vacuum tubes in the WARMER R2R primarily serve as voltage amplification buffers. They are not power tubes, which significantly extends their lifespan. Therefore, under normal usage, there is no need to worry about tube replacement due to lifespan concerns.

2.FiiO products are purchased by many general consumers and entry-level audio enthusiasts. Exposing tubes externally could pose safety risks, such as accidental burns (e.g., to children) or glass breakage leading to injuries. Unlike experienced audiophiles, these users may not have extensive knowledge of vacuum tube handling.

Replacement is possible and is not difficult in practice. However, only official tubes should be used. Third-party tubes are not guaranteed for compatibility or safety.