New Headphones

In the last 5-10 years a lot of new and EXPENSIVE HP's have been produced. I own a modified Hifiman HE-6 and the Sennheiser HD 650. The HE-6 is driven by my stereo power amp (Primare A32) with WyWires Red Series XLR cables and sounds fantastic. Alas curiosity is lurking. Are there any HE-6 owners/lovers (past and/or present) who've added or moved on to newer HP's for increased sound quality? Which HP's were added and what did they add that the HE-6 didn't give? (And in fairness) what amp did you use to power your HE-6 and what HP amp are you using to power your new HP's? I've owned (then sold) the Grado SR60 & GS1000E, Sennheiser HD 580 & HD 800, and the Audeze LCD-X. I've also owned and sold the Sennheiser HDVA 600 and Violectric V281 HP amps. Both were very good (but Violectric was the best of both) for my headphones. The first time I heard the HE-6 I was in love with it's sound (even unmodded) & was smitten by the bass. I'd never before had HP's where I FELT the bass vibrate my ears and head while having a detailed mid and upper range like the HE-6. Is there better? I've looked at the Hifiman Susvara HP because it also needs a powerful amp (I wouldn't need to buy a new HP amp) but that $6000 price tag is prohibitive. I've read the less-expensive HE 1000 V2 is pretty sweet, too, though not as sweet as the Susvara. I've also considered upgrading my HP cable to the WyWires Platinum which would be a lot cheaper than buying a new HP. I know Alex of WyWires makes a superb product and I wouldn't be disappointed.  I'd appreciate any and all input on this matter. Should I be content or go looking (listening)?