I bought a HUGO for a second system in my vacation home so I could use it portably and selling my Vega as a result. I figured I would use it with Sennheiser IE800, which led me to HD800 which I didn't care much for with the HUGO. Then I purchased the TH900 which were wonderful to listen to. Very musical headphones, however, they didn't quite live up to my reference system (which I never expected any cans to live up to) consisting of REF10/GS150/MSB Diamond Plus/Nola Concert Grands (ribbons). I next tried the new McIntosh which were good but again missing something on the HUGO.
Which led me to the LCD-3F and X. I figured, after reading so much on these threads about the need and/or desire for both a closed and open can, I would try the Audeze. I was "told" I would fall in love with the 3F. Well I fell in love, but it was the with the X. I had both for an extended trial, decided the X most closely mirrors my reference I absolutely love them to the point I found myself almost never listening to the Fostex, regardless of the "negatives" of an open can, especially since the Fostex do have a fair amount of leakage.
To make a long story short, I wound up selling my Fostex. I am not denigrating the Fostex in anyway, which I though were wonderful, however, for me the X are just another level, one where I don't feel a major compromise relative to my reference. I couldn't recommend these more highly. From my perch, from first listen they were better in every way than the 3F and the most enjoyable I have ever heard the HUGO, including my second system.