It’s an Airlink BPS5120MP. Yes it is expensive, albeit massively less-so than an equivalent audiophool-branded product - if you can find one with this much current headroom. It also needs you to be able to wire it up - Airlink make less faffy options - albeit for a bit more £.
For my system it makes a very significant difference, and that comes after years of refining my own passive power filters.
As well as isolation, I’m also using it to drop the voltage seen by the system from the usual ~245 volts down to ~235 volts, and that is likely to be helping, given the majority of audio kit is designed for Europe’s nominal 230VAC rather than the ~240VAC we get in Britain.
It’s CE and EN61588-2-6 compliant - which is abundantly good-enough for me. Airlink make these things in very large numbers for a great many end-users - audiophools being the least of them - and as a registered company are fully and ruinously liable if end users are harmed by their products.
I’m actually now sorry I didn’t get one a lot sooner, it works that well. Subjectively it’s the full ‘that flawless sound you only get at 3AM on a sunday morning’ effect - everything I play sounds smoother, quieter, calmer and more realistic.
Being a pessimist, I’m always ready to be disappointed, but this is the opposite - better than I expected. It’s the biggest upgrade I’ve made this side of better speakers.
I’m using a high-current DC-blocking filter to feed it because it’s a huge toroidal transformer, so saturates loudly when there’s DC offset on the mains, as demonstarted with a hot-air gun at half power! I’d not use an isolating tx without it, as you’ll never be getting the best performance.
ALL mains treatments involve a compromise, and all of them - if poorly implemented or used incompetently - can do nothing, or actively do harm, for a host of reasons. This thing - by breaking the line of noise transmission to a very significant extent seems the best compromise. Just so long as your back and your ability to tolerate ugly lumps of metal allow it…