I know this is bucking the prevailing thinking but yes there can be a benefit at 1 watt. I will soon be completing my comparison of the Yamaha RX-A820 to the same system using a separate ATI AT522NC amplifier.
A friend and I had no problem in single-blind-tests (SBT) distinguishing between the two when level matched as best we could to approximately .1 DB. The improvements were wider soundstage, quieter background, cleaner upper end.
Power usage was between 2 and 6 watts. Neither amp was close to clipping.
In this case, the comparison was between the Oppo BDP-105D driving an amp directly and the same source through the RX-A820 so it is not a comparison of just amplifiers, it includes the pre-amplification and volume control in the Yamaha.
- Rich