TI, current production, JRC current production. They were rated identical in tests.
Decoupling for all was identical, 10nF C0G across power pins, 1uF X7R from power pin to ground, below the IC. 100uF Os-Con on each rail within 10mm of the IC's, power lines decoupled via ferrite beads.
All IC's SMD, soldered. Configuration differential amplifier as balanced DAC post I/U conversion summing amplifier from dual DAC per channel.
Multiple otherwise identical units off the production line were modified, secondary testing was with a headphone amplifier, again as above.
Testing was blind, different devices identified by geometric symbols. Testers were unaware what difference, if any, existed between units.
Tests were preference / marks out of ten with decimals across multiple categories as well as a numbers of psychological proxies.
Testers were allowed to interact freely and according to their desire with the units, except opening up to see what's inside.
Testers could select music to their liking and were compensated for their time on a time basis.
Thor
