Pawel, to compare X1 (open) and H6 closed, like you said its just not a fair comparison. Both serves different purposes and price point. But for portability and super super easy to drive headphones and comfy, its one of the best for travel and commute. The cable replacement does improve the slightly, marginal but not night and day. H6 sound stage for closed earphones are ousted the p7 and 2.0 in my opinion. After months trying and auditioning dac/amps, I finally went with DragonFly Black(DFB) 1.5. It does improve the space and sound stage by a noticeable margin(20-30%). Just make sure to burn in the DFB for 24 hours. By far this is the best combo for on the go for me or while at work. It depends what you want and what's your benchmark of quality music is. Guess you just have to do some soul searching.