I used the attentuators with my Hiface to great success. I ended up with 10db at Hiface end and 15db at the DAC end. What I noticed most was a deeper soundstage, more "air" around instruments and a more relaxed sound from my DAC. Brushes and cymbals took on a much more realistic sound, a lot closer to analog.Then i went completely craxy and mounted my Hiface inside my DAC connecting it directly to pcb, thus eliminating the RCA/BNC/Cable dilemma!!! So.... now I have 3 attentuators I'm not using. A 6db, a 10db, and a 15db.
If anyone can use them and wants to have them, send me a PM.