Need new headphone setup.

If you currently use cheap ear buds, then maybe another option to consider is something like Etymotic “In Ear Monitors” (IEM)?

Even with an iPad dongle, or with a standard iPhone 1/8” audio out they are surprisingly good.

If you are looking at cans. Then you probably want to select the can before selecting the amp, so that you can ensure the that required output impedance works.

Half the time I use the IEM without a pad, as their noise blocking is pretty good, so I use them like ear plugs. But I also have a few Etymotic ear plugs handy most of the time as well.

How much portability do you want?  Your iPad is already a streamer, so I would just buy a dongle DAC, like the Dragonfly Cobalt.  If you buy a streamer, DAC and amp for headphones, you're likely limiting your listening to one location and eating up a chunk of your budget (since you're essentially building a second mini-system).

I have several headphones and DAC/amp combos and, frankly, my cheapest, Dragonfly Black and Grado SR80s, sounds pretty damn good.  The Black, the new SR80x and a USB/Lightning adapter would run you a bit under $300.   A Cobalt and Grado 325x would run around $650.  Lots of headphone choices out there - but keep the source simple.

Thank you very much for your suggestions.

‘Sounds good to me.