Tubes vs. solid-state: FiiO K13 R2R vs. Warmer R2R

The FiiO Warmer R2R arrived with a lot going for it on paper. Linear PSU. Tubes. VU meters. An in-house R2R module. At least three bell rings for audiophile catnip. At US$349/€379, it looked the part. My January review gave it extensive coverage but stopped short of a DAR-KO Award: […]