Recommended Upgrades for Jolida JD202

I have about 200 hours on my new Jolida JD202 amp, and so far I've been quite impressed with it. As stated by many others, it is amazing with female vocals and acoustic music.

I'm looking to invest in some upgrades, and hoping people can comment on where the best bang for the buck is. I'm looking to upgrade the power cord, interconnect and tubes (I'm set on speaker cable). If there's some options that work better than others please share your experience. And if there are other upgrade options to consider, I'd love to know as well.
If they are stock tubes, new ones can make a nice difference, even inexpensive ones. It appears that Jolida counts on buyers rolling tubes so they don't splurge there.