Hi Paul,
Yes, definitely, but then it was the last thing to go from what had been an all-Naim system. I'd kept it on for a while, but I was driving Linn Kabers at the time and they seem to be at their best with as much power as you can throw at them, short of going active. As a hopelessly simple comparison, following the nomenclature of Naim amps, IIRC the 557 would be the equivalent of a NAP600.
And as the rest of my system had tended towards Meridian by that point, including moving to a digital preamp, it was the way to go. DAC at the time was a Benchmark DAC1 so I could also try the balanced outs into the 557, which seemed to make a meaningful difference.
I have DSPs now though.
S