Output transformers with exceptional bandwidth, dynamic range and low distortion for low power valve amplifiers using a plate choke and isolating capacitor. Combination cores using a sandwich of highest grade low loss (M6) grain oriented silicon iron and Mumetal (76% Nickel) laminations. The Mumetal which has the property of minimal distortion and very high permeability even at very low excitation carries the low intensity and high frequency sounds. The M6 carries the full power base sounds. Multiple interleaved winding sections to maximize bandwidth and ensure clean transient response. Low copper resistance to minimize losses and maximize loudspeaker damping.