The recently launched DIA-250 and DIA-400 integrated power amplifiers from the Danish manufacturer Gato Audio are both equally well suited to serve as the centerpiece for a home stereo system whose owner values aesthetics as much as performance. Priced at $4,500 and $6,000, respectively, the DIA-250 and DIA-400 share the same compact and curvy form combining stainless steel and wood, while delivering different peaks of pure class-D power. The DIA-250 has a lower power output of 250 watts per channel—plenty of …