After reading so many positive reviews and experiences, I finally bought a PSM156 myself (with upgrade to Classic plus power cord) to replace an Audio Quest Niagara 1200. My set already sounded quite nice, but probably caused by mains fluctuations and external influences from power supplies and electronic devices in the area, it was a lot less pleasant at certain times. It just wasn't consistent in sound quality. The Puritan almost completely solved that problem right out of the box. But moreover, even if it wasn't properly burned in, it improved the SQ in several aspects already.
I experience a (slightly?) deeper sound stage, it is less cluttered, less chaotic, especially with orchestral music. In addition, I hear a deeper and more tightly defined bass and there is more spaciousness: the acoustics of the space around the instruments are displayed better and more beautifully. Any sharp edges in the high tones of some instruments have also virtually disappeared. All in all, it has undeniably brought more calm and tranquility to the music.
As you can imagine, I am already very happy with it!
By the way, my set consists of a Cambridge Audio CXN V2 streamer, a Matrix Audio X-Sabre Pro dac, a (vintage) Marantz CD 17 KI Signature SACD player, a Cayin A88T MK2 tube amplifier and finally a set of Martin Logan's Ethos hybrid electrostatic speakers (with active subs).