I have personal opinions about both of those products, but I will try to address what I feel is the general consensus about both of these things.
I think you have a misconception of what all the hate is actually about.
The reason why people "hate" the newer denon headphones is because the previous series sounded much better. It had much warmer bass and a much more natural sound.
The newer headphones are actually a bit thinner and tiny by comparison.
But that does not mean they sound bad. It is just that people feel like they can buy something better for the same amount of money.
There are multiple reasons why people hate FiiO. Most of the times there is some type of hate towards FiiO is when people are trying to use them as desktop amps. But FiiO does not get too much hate when you are strictly talking about portable amplifiers for cheap simply because there are very few other options.
TL:DNR = The things you bought just so happened to work for you because of the environment in which you are using them (I am assuming you are using your system as a portable rig). If you are only using your rig as a home system, then all the hate is definitely deserved.