just don't draw too many concrete conclusions about a type of tea or tea in general with your limited experiences. Maybe too early to judge?
Sometimes something as simple as changing your water source or finding a kettle that is actually suitable can make a huge difference in how a tea will turn out. To see if its your water you can try to cold brew your gunpowder for 6ish hrs in the fridge with some dasani or aquafina bottled water. Taste that and compare it to how it tasted when you brewed hot. If it tastes pretty similar then it might not be your water. If it tastes almost like a totally different tea, or has very pronounced notes you did not detect before then it could very well be a water issue. I think it is pretty important to figure this out first before you go on wasting money on tea that has no chance of turning out good because water is sub par to begin with.
Also vendors quality varies a lot. Adagio is not the best example out there imo, sorry. Like I said before, better to get from an overseas vendor that has been proven reliable and doesn't mark up too much. Many US vendor sites with tons of different teas don't do a very good job sourcing since they often source from a middleman's middleman. What you end up with is decent/mediocre tea at an affordable but inflated price (again imo).
But alas, people go for what is easy, well marketed, and familiar. A shame with so much good stuff that is out there for the same price.
Hope you find something you like