The last R1 / R10 component to appear, as developped by the team that crafted the other R1 units.
The SS-R10 high-end electrostatic loudspeakers appeared even later but that was more of a one-man project launched by Keijiro Maeda and finished by others when the former sadly passed away.
The TA-NR10 is in fact an updated and ameliorated TA-NR1 :
bigger, heavier, fully (gold-plated) MOS-FET equipped, 6N OFC wiring, dual-layer 70µ OFC copper circuit paths, OFC power cord, high-carbon steel chassis, Germany-sourced super-permalloy core line transformers, brass terminals, 10kg / 1kVA toroidal core transformer, 25A diodes. Etc.
The enclosure is made of 2,1cm extruded aluminium and, last but not least, the heatsinks are made of pure copper - 10kg each !
Unfortunately, unlike the original TA-NR1 which sold fairly well worldwide, the NR10 were on order only, much more expensive and are now complete unobtainium.
If the R1 and R10 units gradually vanished from the catalogs throughout the mid to late 1990s, Sony kept them in fact still available in Japan on order only : dedicated service and spare parts were available as well until at least 2002 or 2003.