I added 2 Purons to the dedicated wall outlet & 2 in a Synergistic Research PowerCell 8SE that is first in line. It took longer than I expected, however, to hear changes/improvements with only the pair in the wall outlet. After several days, I began to hear more transparency, detail & depth. All pleasant, not so subtle, improvements!
Then I added a 2 more Purons to the first pair of receptacles in the SR distributor. Almost immediately, there was a doubling, if not more, of the attributes I heard when only 2 Purons were plugged into the wall outlet. Additionally, there is a greater emotional connection to the music. By that I mean, you have a much better feel for the space in which the recording was made. Musicians have a more precise location on stage with with more space between them. All adds up to a soundstage with greater depth which, I find, is more difficult to achieve than width.
I believe the Puron plug-in filter punches well above its weight class, especially when adding more than 1 or 2. There seems to be a cumulative effect. This is undeniably one of the better bang for the buck upgrades I’ve made.