I wanted to draw attention to this network filter by Network Acoustics. I have the silver version which is placed between my switch and NUC. It enhances all the usual hi-fi virtues of scale, dynamics, tonal purity, removal of harshness etc. But it is its ability to allow detail to shine through that is remarkable. I was very surprised by how good it is.
At first, focus was a bit off but after some burn-in it became first rate. [Will people who do not believe in burn-in please ignore the above. I do not want to debate the issue. But I can think of no better component to demonstrate the benefits of burn-in than the silver version of this filter.]