Smaller, later sibling to the TA-N80ES bestseller, the TA-N55ES was... also a bestseller !
The N55ES was explicitly made to accompany the TAE-1000ESD Dolby-Pro Logic preamplifier and could be complemented by the small TA-N110 as well.
The N55ES uses the same toroidal trafo as the european TA-N80ES (aka mkIII) and two pairs of Sanken 2SC2921 / 2SA1215 for power output.
The main smoothing caps are 63V/12,000µF ELNA For Audio ; the four caps all rest on the same material as found in the TA-NR1 and TA-NR10, grainy resin cast - but here in bright red !
A big black heatsink keeps everything cool and all this rests on Sony's G-Base, named after Gibraltar.
Selling in Japan just as well as elsewhere, the N55ES was a TA-N330ES there and was fitted with a second input and related front pot to switch sources.
Tomaz Gersak (gerchy) from Slovenia informs us that there are in fact three versions of the N55ES, as there were three versions of the N80ES which I'll name alike for the sake of simplicity :
> N55ES Mk1 : silver RCAs, round transformer,
> N55ES Mk2 : gold RCAs, round transformer,
> N55ES Mk3 : gold RCAs, square transformer.
I have never seen the square trafo but there are thousands and thousands and thousands of TA-N55ES playing around the world nevertheless, whether in strict 2-channel systems or within home-theater systems.
Pioneer (M-72 etc) and Yamaha (MX-1000 etc) may have made similarily priced amps in the 90s but none sold as well and for so long as Sony's N55ES !