The Eastern Electric is a real winner! Very toneful and tuneful, inner details with excellent bass. Put the unit through its paces with a pair of Altec model 18 604-8H speakers. These speakers are merciless for the correct tonation, balance and details. No sibulance, but pure musical tones, depth and structure. The M520 is extremely well built, great output trannies, can use another preamp of choice. I liked the zero feeback mode, in pentode class A operation 24 watts per channel, will put many SET amps to shame. Extremely low noise, great PP dynamics and tone.