Hello,
I just wondering about buying new gear (TOPPING DX3 Pro+) to my headphones and i’m not sure that will improve sound and worth it.
Currently i have denon Denon AH-D5200 plugged into Audient id4 mk II. I’m using it because have XLR microphone and these headphones are easy to drive so bought audio interface to have only one device.
Should I consider buying dx3 pro+ for headphones and speakers in the future or it doesn’t make any sense?
Do you like the sound of the D5200 out of Audient and you do not plan really REALLY to buy speakers/more demanding headphones? If yes, the answer should be clear clear 
I mean, you cannot go wrong with Topping DX3Pro+ as well as it is so multifunctional little device with great measurements, but you would have 2 devices this way, cable mess etc (just in case you may wonder - it does not support TRRS input, so no in-line mics possible). The sound quality improvements would be probably within a margin of error or placebo based on my experience.
I have Topping driving both my speakers and IEMs/headphones and I love it though
I would say yes absolutely…but more so an amp before a DAC if money is tight. where are you located and how much would you be willing to spend?
Looking for something under 200$ and thats why mention TOPPING DX3 Pro+ cuz heard thats really good deal. Good thing is my my mic (shure mv7) have xlr and usb connection and i forgot about one thing 
By usb i can use software where can adjust more options profiles boost etc. To sum up if i decide to buy dac/amp combo for headphones i will sell current audio interface so it will be “upgrade” Good thing is quality of mic with usb connection is almost the same in my opinion, later had to buy audio interface cuz of work. Now i don’t need it thats why im wondering about new hardware 
take a look at the iFi Zen Air DAC and Zen Air CAN. Amazon gas em for $90.00 each, 10% lower than usual list.
looks good, but preffer one device dac/amp combo
You may also check this SMSL C200 DAC/AMP for 220$
So. It seems like you don’t need a new dac/amp combo or stack. It looks like you want one.
Nothing wrong with that. Most of the shit we buy is cuz we want it, right 
For me the very simple question would be “Is there something else I can buy for $200?” If the answer is no, then a DAC/AMP is a great idea. (My vote going to @pylaczynski 's great C200 suggestion)
But if there’s something better, audio or non-audio related, you could buy for that money… I’d jump for that. There will be $200 DAC/AMP’s next month too. Next year. Next decade!
well, the Zen Air DAC is a combo unit…but adding the Zen Air CAN will net you a bit more power and functions. the difference between the Air DAC and the Zen DAC v2 is the Air doesn’t support MQA or offer balanced output. MQA is a very divisive topic, but if you use Tidal you might want to have the ability to decode that natively rather then via emulation. The Zen DAC v2 costs a hair more than what the two Air would be together.