Some impression after using it for more than 100h+ with my Hd598's. It has made the sound "fuller", more bass impact and punch, without losing detail, maybe even gaining some. Regarding soundstage it widens it a bit and makes it more "refined" and images it bit more i would say. When i forgot this amp home when i went to alps and i listened music without the amp it just feeled...wrong , the music wasn't (rock, pop, disco mainly genres from 1960-1990) there almost it feeled "empty" to my ears. So for anyone with a HD598 i HIHGLY recommend getting this. For only around 140$ this really makes the HD598's sound SUPREME. Listening some ellie goulding "lights" through these, gives me goosebumps
You mean $100 right? If you payed $140...I'm sorry lol.