You can’t judge the 6 SE v2 with the power you have. It needs 90 hours of break-in, not BS in the least. Every single mylar membrane speaker (7) and headphone (12) that I have owned demonstrated it clearly. Never heard break-in on ribbons, and most dynamics. Woofers over 10" that are have thick paper also change with use (go a few Hz lower by measurement, and the range of motion increases too).
The cable it comes with is not only not nice to deal with, its sonically inferior. No other headphones (DCA, Audeze, Senn) I have had multiple copies of demonstrate this. But every single HFM cable is not up to snuff. HE-6, 500, 6 SE v1, v2, 560, 5 SE, 400i, Sundara, 5LE, HEX v2. Also the pads are not a good match in all the round cup models I listed and a few more that I didn’t.
So why put up with that? The drivers are for the most part superb at the price. Make a O2 free cable or buy a good cheapish one such as Custom Cans out of the UK. Get a DCA Ether Angled Lambskin pad, take off the rear screen (or get one with a more open mesh), do the fuzzor mod as described at Head-Fi, EQ it, but the popular settings from say crinicle are bass happy and do not deal with CSD problems at 3.5 and 9k. Do all that and it will out perform the Arya, LCD2, and the Clear assuming you have 4 wpc @ 50 ohms or more.