Difference between Bluesound Node, Node 2, Node 2i, NodeX

I have a 2i that I  bought refurbished 4 yrs ago and upgraded power supply.  That runs to a Topping D90 AKm version.  I am getting great detail, non fatiguing sound.  I will keep this til it fails.

If you are using an external DAC, I would start at the Node 130 (model after the 2i), as it is the first model with USB output....which you may use at some point in the future. Definitely upgrade the power supply to something like a Teddy Pardo or the like, I use an LHY linear power supply upgrade ($279).....power upgrades make a big difference on Bluesound Nodes

A Bluesound representative told me the least expensive upgrade to the Node X was replacing the stock power cord. I hooked up a Transparent Audio Hardwired C7 power cord and was very happy with the changes. I am currently running coax out to my Moon DAC and I am pleased. 

I upgraded the stock power cord on my Node2 to a Nordost Purple Flare which fits without any adapter. (Digital outputs to DAC: ADI Dac-FS for my main system.)