No worries. In the last 1.5 years so many terrific affordable DAC/Amps have been released that it is hard to recommend just one! And there is no PC Part Picker for newbies looking to purchase their first high end DAC/Amp, so happy to help. You are going to love the A90+HD800s.
@Jimbob54 Do you have an Enog2 Pro? How do you stack it with an amp & cable manage when the XLR OUT and SPDIF IN are on opposite sides?
Not unless you want to donate your cash to Sennheiser. You already get a 4.4mm balanced cable with the HD800s that will deliver the exact same power as the XLR. I have an after-market cable because I wanted something shorter than the stock 10ft ones, unfortunately you are going to pay at least $100 for one because the HD800s proprietary connectors are 3x more expensive vs other headphones.
You will need two 3-pin male to female XLR cables to connect the DAC to the Amp.
These are $18 each for the 1ft option, and use very high quality components from Neutrik and Mogami:
XLR Interconnects
Here is a whole thread about XLR cables if you want other options:
https://www.audiosciencereview.com/...cent-inexpensive-relatively-xlr-cables.14328/