You are exactly where I was a couple months ago. I had Airpod Pros and Bose QC35IIs, but I wasn't satisfied with the sound. I did some research and determined that I wanted the Sennheiser HD 650 headphones. I learned that a DAC/AMP would improve the sound quality, so my first purchase was a DragonFly Red. I connected it directly to my laptop and iPhone with a camera dongle. I was blown away at the sound. Really great sound for a little over $500 total (This was before I learned about the Mass 6XX sale going on now).
I kept reading and learned about the Chord Mojo. I picked one up cheaply on eBay and I loved that sound even more than the DragonFly Red. I was planning on using the Chord Mojo as a desktop DAC and the DragonFly Red for mobile. Then, I wanted an even more mobile solution so I purchased Shure se846 cheap on ebay and a FIIO BTR5 Bluetooth DAC from Amazon. To feed my addiction, I got a Bottlehead Crack paired with a Schiit Modi Multibit DAC just yesterday. My wife thinks I am crazy, but I guess that just makes me a true audiophile.
So let me compare and contrast the DACs.
The best mobile solution for use with the HD650 headphones would be the DragonFly Red. That's because it has sufficient power and is very easy to connect to your laptop or iPhone. Since it is powered by the laptop or iPhone/iPad, fewest number of cables. But since your iphone or iPad only has one port, you need a separate cable to charge the iPhone or Ipad, but you can get a dongle that allows you to connect the DAC and power.
The FIIO BTR5 is good for my Shure IEMs, but I find it a bit underpowered to drive the HD 650s. I prefer the sound signature of the DragonFly Red over the FIIO BTR5 because I prefer a warmer sound. The FIIO BTR5 is more neutral and clear and lacks bass punch and warmth. But it is a perfect match with my Shure se846s with the black filters.
The best mobile sound is with the Chord Mojo. I will use it as a travelling desktop set up. Wherever I set up my laptop, that is where the Chord Mojo and my headphone stand goes. It requires a lot of cables, it's heavy and gets very hot. But it sounds great.
By far the best sound for me is my permanent home listening solution which is the Bottlehead Crack with Speedball, Cap and Pots upgrades. This combination produces truly glorious sound.
For me, this is not over kill because I like all of the different sound signatures and I have specific use cases for all of the combinations.