I replaced two bridged MC2100 amps with a PL 400 in around 1973 or 74. The PL sounded better to me, a lot better, but it all depends on what sound you like. The Macs were warmer, had lush sound, but were not as clear on the highs and had less control of the bass. This is subjective of course, but that Phase 400 is still with me, the Macs are long gone and not much missed. Make no mistake, the Mac amps were built like tanks, the Phase was built cheaply, but again, taken care of, it has stood the test of time. I am going to have the PL400 gone over and modernized just because. All this old stuff is fun to have and to mess with. I have owned a lot of amps over the years including other Macs and Marantz, ARC and Adcoms. They are all good, I have never had a bad one.