I found that the JBL 306P are better than my Yamaha HS-8s. They just have a cleaner and more powerful sound, especially when cranked up. The 306P are also well cheaper! Interestingly though, I experimented with both systems stacked on top of one another (306P on top of HS-8s), man do they sound great. And this is even without a sub. It means I don't need to crank up the total volume near as much and it still has satisfying power to the sound. Highly recommend combining these. It's like they cancel out the bad of each other.
The listening experience is what counts at this price, not the quality. Don't attempt to analyse speakers for their accuracy for anything in this € range!