hey man, I'm new to the IEM hobby and I bought the dioko 2 months ago.

1. You really don't need an amp/dac to enjoy this IEM unless you want the overall volume to be louder. Although I did buy an amp specifically for the dioko's (I just like some of the songs in my playlist to be louder) you're really not missing much in terms of sound quality without it.
2. I felt like the eartips provided by 7hz are good enough and they fit great on my ears but if you want to get a better listening experience I'd recommend buying better ones.
3. I'm using an old Iphone 6 for daily use and the dioko's pretty much have the same quality with or without the dongle so it's not necessary.

You can just enjoy it straight out of the box so don't worry about the other accessories