Deze trompet is het resultaat van een intensieve samenwerking met Adams artiest Amik Guerra:
"You know, as a professional musician you always want to have an instrument which is just, expressing what you have in your head. In some ways it's like an amplifier of what you have inside. And you've got to have the best amplifier.
The relationship between a musician and an instrument is really close. As I came to Adams with the idea of the A4 I had really specific needs and ideas about how I wanted the horn to sound, the flexibility, the playability the intonation... It's also what I needed for my shows. I hear the sound in my head, but I needed a hand which will put this together.
And of course as a musician and not as an instrument builder, you have all these ideas that sometimes are not even compatible, and you need someone who is going to make them work together. We had a really long year of work with Miel Adams to find the way, and these needs I really wanted, and all these ideas which I wanted to put together. And at the end of one year of work, i was like: Oh, this is the instrument I was dreaming of for my whole life! And it covered everything I really wanted and needed in my horn."