Sony STR-DA1000ES - Manual (Page 13)

ES Receivers V3.0 Page 13
The discrete output FETs of the STR-DA2000ES.
Toroidal Low Pass Filter
The Low Pass Filter is a crucial stage in any digital amplifier. The filter
must have a turnover frequency high enough for high-resolution audio, yet have
a cutoff characteristic steep enough to suppress high-frequency noise elements.
In this way, the filter has a major influence on sound quality. That's why the
engineers of Sony ES selected the filter parts carefully and methodically. Instead
of choosing less expensive cylinder-type coils, the ES engineers chose exotic
toroidal coils, optimized for sound. Customers will never see these toroidal coils,
but they will hear the benefits in clean, open, non-fatiguing music reproduction.
The toroidal coils of Sony's Low Pass Filters are more expensive. But
their contribution to sound is more than worth the price.