Hello, I know about your question, but I don't speak Italian. I hope it won't cause a problem for you. For Bose integration you need to know the amplifier input power in your car. I integrated the Alpine ilx-F309D into my alfa romeo mito and it had a preamp output with 4V. It should be 6V for my BOSE amplifier but I installed it anyway. As a result the maximum volume is 25% lower than it should be but other than that it works perfectly.
If you have higher output than your bose input at JVC, your amplifier can burn (or make distortions at sound) so better to learn about amplifier input first. Alternatively you can cancel whole amplifier and directly connect your speakers to JVC. Most people doing it because it is way more easier. But I dont know how it effects audio quality.