I have had 8330 in my listening room for three days done some measurements and I own 8340.
They sound and measure VERY similar but the 8340 can play louder and goes deeper in bass.
Iˋm afraid the comments of missmatch of element is incorrect . The 8340 has a crossover frequency slightly lower than the 8330 speakers. But they dont sound worse because of that, they sound better/or the same . There is better amplification inbuilt in 8340, one of the things thats better than 8330. The 8340 goes down 10 Hz deeper and can play a lot louder to.
If there was something like missmatch , then the 8350 would be even worse, since it uses a big 8 inch bassunit combined with a small 1 inch tweeter. And thats not the case, the 8350 sounds better/or the same as both 8330 and 8340 , But the 8350 can play louder and goes deeper.
The soundquality of the Genelecs reflects the price. More expensive - the better the sound and with higher spl .
In my opinion , if you are an audiophile , you should drive the 83xx series with a digital source and digital output to the Genelecs to gain the best quality - before even thinking about buying more expensive 83xx speakers.
Im my testing - the 8330 with digital input sounds better and a bit clearer than 8340 with analog input, and 8340 with digital input sounds better and a bit clearer than 8330 with analog input.
Below is two of the measurements of 8330 , one on axis and the other 15 degrees of axis.
I cant see any peak at 1,8 kHz such as Amirm measured.
As I used a sine-sweep in my room, the measurements are only accurate from 1 kHz and upwards. The mics used was line audio om1, accurate +-1 dB 20-20000 Hz.