In normal listening room, are you shure?Yes, and the difference is probably that the dsp crossover in 8330 has slightly better performance with higher order crossover slopes than the analog active crossover in 8030c . I would also guess that the 8330 has the same tpa 3118 amplifier thats inside the 8030c.
Both of those loudspeakers are very good performers distortion-wise when you think about how small they really are.
The distortion measurements by Amirm are made with only one loudspeaker. With two loudspeakers in a normal listeningroom with some roomgain, you should get about 6-12 dB higher SPL , in the lower frequencies.
Just looking at the measurements, one can get the impression that both loudspeaker models should sound about the same. Thats not true - feeding the 8330 dsp crossover directly with a good digital signal would sound slightly cleaner .
I would say that the price is right for both 8030c and 8330 , regarding sound quality.