Having the Node 2i also but using a reference external DAC is not the issue at all. We also have the Aurender and we will compare this week also using an external DAC.
You can upgrade the amp for not that much and see how you like something when you purchase new.
IMO having had a ton of amplifiers and also we build our own, find a nice BEL SS power amp. Musical, not that expensive, etc. These amps sound fantastic even the old early models. They are also easy to upgrade when the time comes. Other than that for SS you have the HK Citation power amps that are excellent and not very expensive.
Happy Listening.