Sure yeah it's improved. Power supply/regulation, additional crossfeed, digital volume control and 3 step gain settings, but the overall design of the amp section is similar. I asked him the same question and other than the improved/added features everything else is similar.
Besides, how can you hear a "cleaner" sound when it's already clean? I was thinking the difference must have come from listening with 2 different opamps. But then hearing differences is a matter of subjective opinion.