This has to be one of the most analog sounding DACs that I have heard. One reviewer commented how much the DAC was voiced to sound like Rega TT or in other words how vinyl-like. I totally agree! Liquid, smooth, organic are words that come immediately to mind. In fact, I cannot believe my ears are listening to a digital source!
I have tried the various filters but playing 44.1/48 through Rega's USB, I preferred #1. The other filters caused a bass hump or thump which I found very fatiguing. In fact, I had the Rega DAC On #4 for some time, only to discover that the bass hump was due to the filter. It gave the bass a hollow sound. In the manual, Rega recommends #1 as the default.
This DAC is highly recommended! Build quality is beyond reproach.