@mikhailark couple of things here….
1. I agree with you that essentially what the iFi is doing should be part of a well designed streamer. And it probably is and hence the reason it makes absolutely zero difference in my system. However, I do not know what is and isn’t built into my streamer. If it protects against surges it’s worth keeping it in the chain for me.
2. Your urban myth about Pass. Nelson Pass is not against aftermarket power cords. He does encourage using certified cables though. I owned X250.5, XA30.8 and X260.8 mono amps and XP-12 and XP-22 preamps. I can tell you first hand that these components benefit from high quality power cords. Every Pass Labs manual has a section about power cables. It’s available online check it out. And don’t spread disinformation. You’re becoming annoying in more than one way now.
3. I owned Network Acoustics Eno Streaming System that includes a passive filter with a captive Ethernet cable as well as a separate Ethernet cable that would connect the filter to the router. It makes a difference. I happened not to appreciate what it did in my system and I sold it. But it doesn’t mean it’s a bad product or a scsm. It works. And the way it does is it throttles data transfer at 100mbps which is thought to be optimal for streamers (for some at least). Depending on the implementation it might work with some streamers and might not work with others.
Forget marketing and don’t get pissed off at companies making products that don’t align with your narrative. You’re fighting windmills. Go out there and try some of these products. If they don’t work, return them. Rather than posting theories you can’t substantiate get some real experience with this stuff.