I ordered the X7 initially and had it for a over a week, before returning it for the XDP-100 and then returning it to finally order DP-X1.
I returned it for similar reasons to
@McCol, namely EMI issues while streaming. Initial design issues (are they fixed?) killed part of the hype I think.
I wouldn't say the build quality is bad, but it's not as premium as DP-X1 for sure. It's more bulky at it's quite thick, but that's understandable as it packs a big 3500 mA battery to power the hungry ESS9018 that's not designed for mobile use. Tolerances are good but the material doesn't scream premium. The screen is nowhere near DP-X1/XDP-100 quality but that could be deemed secondary.
As for sound, It packs more bass punch indeed, but bass are less defined and control to my ears. I didn't really pegged it as V shaped and I would have said the X7 is warmer than the DP-X1. Treble are nowhere near as refined, it's buttery smooth but it lack the detail of the DP-X1. Mids are smoother and a tad more forward. Overall there is less clarity, separation and transparency. I guess the X7 might pair well with analytical / cold headphones that might explain why I liked it less than DP-X1.
To me the DP-X1 is more 3D and it does have a sound back bone and I would peg it as technically more refined than the X7 but that's probably down to personal preferences and also which headphones / IEMs you intend to use them with.
One thing it has for it is sharing the same 2.5 TRRS for the balanced cables, that could be a deciding factor if you have invested already