Using 2x V5i opamps in my Xonar Essence STX II. I upgraded from genuine LME49990 dual-mono opamps. The V5i is excellent for the card’s Dolby Headphone feature. The opamps’ midrange focus and increased detail are awesome for movies and create a very nice focused centre image for dialogue. The V5i definitely have a colour to them, with some taming of the bass and treble, so for music, I would not want them as my only source. But for occasional use, the midrange can be quite addictive for music, too.