Hi, end-game means I'm likely not to change it in the next 5/10 years as something better will come into picture. I just need to like the looks, for example, I don't really like the DX3 PRO.
Budget around 500 usd would be ok, I could extend a little if I feel it justifies it. I ordered a DX7 PRO but the seller is saying they will come in stock in 2020 -_- so it made me think again about my choice.
So you want something that you can use for 5/10 years, and something that looks good if I understand correctly?
Well on that front, audio is wayyy to tumultuous of an industry to know whether gear will last 10 years. Especially with planned and intrinsic obsolescence running rampant in all product industries in the modern era. What I mean by that is devices are made purposefully to not last long, as it's not economically viable to give someone something that will last them 10 years without charging them up the ass for it. If it does last 10 years, think of the company doing that as either making a mistake, or you just getting lucky.
As for the looks, I cant really help there. The topping you ordered seems beautiful in my eyes. Believe it or not I had an infatuation for that device for so long I consider sometimes selling my RME DAC + 789 and just getting the DX7 Pro. It also has Bluetooth input which I consider essential from all devices in 2020 past the $200 mark. My biggest problem with it, is Topping's massive paranoia, or inability to move away from the recent scare they've had with respect to output impedence. For whatever reason, they can't or aren't willing to go back to 1ohm or ultra low impedences. Which is a problem for me since I use IEM's as well as headphones.
I also then remember how I constantly make use of the RME's DSP functions. It's simply too much to pass up on.
As for the other devices on your list. You have the Element 2. If I didn't care for balanced, I'd get that device. My only problem with it, is the volume knob design will allow tons of dust to fall through the junction between the knob and the case. If that were fixed, that'd be great. But again, they have the issue of simply no bluetooth input, and no balanced. And at $400, it's too much of a concession for me personally. But their customer service, and being based in the US, is great for residents here.
The Massdrop, well I though I'd enjoy it more than I do. It has so much damn power I am using my RME on the lowest gain, and I still have to back off the output volume on the DAC if I want to have much volume control on the 789 (with it too being at lowest gain). This thing's power is insane. The design is better looking to be than the 887 from Monoprice (same device but a bit better measuring than the 789). If you get either of these amps, you are set for as long as they last. And speaking of which I'd go for the Monoprice for the sake of warranty, they seem to take care of folks and offer a better warranty. The great thing about them is they have everything you could want out of an amp (audibly transparent performance, nice build quality, and power only deaf people would find not enough). It also allows you use a single-ended DAC or Balanced, while still being able to use any of the headphone outputs.
The 789 can also be had for cheap these days (sub $350 regularly from used sellers), so there's that.
You then also have things like the Sabaj D5. Decent headphone output, and simply one of the best devices for the price (i'd say best bang for buck all-in-one). Goes on sale regularly, and if you ever want a seperate headphone amp in the future, you can rest assured with it's DAC section being literally one of the best.
Lots of options really, things like the D50S from topping is also a great DAC that can be paired with an amp like the newest from Gishelli Labs, or the JDS Atom for instance.
I could go on, but just know all these devices you talk about at least come with exceptional performance. We can't attest these devices will last you 10 years, but either which way you go, you most certainly are getting something that will stomp on gear from 2012 you're upgrading from.