I'm not a big poster on here so doubt my opinion will carry much weight but..
I have a Node 2i with the Fidelity Audio interface and a Sbooster lpsu. Had I known about the Polish interface I'd have bought that as he comes across well, and as someone who might help out if any was needed. I also like the idea of supporting a small business.

I tried the iFi and sent it back as it did nothing I could hear for my system, but the Sbooster brought an immediate improvement, and is worth every penny in my opinion, and in my system.
I have no connection to them, but Fanthorpes hifi offered me a (30 day I think) home trial which not many of the other suppliers would give.