With the U18t, 64 Audio constructively explores the limits of what is possible with in-ear monitors. The sound results are completely convincing and meet the highest demands of stage musicians, sound engineers and audiophile music listeners without restrictions. The extra cost compared to the equally outstanding U12t is obvious, with the sonic gain being particularly noticeable in the areas of neutrality and spatiality. Without a doubt, the U18t and the custom-fit model A18t with list prices of 3,299 Euros require a budget that is by no means available to everyone. On the other hand, they demonstrate the upper limits of what is currently feasible in the in-ear monitor sector. The U18t are comparable with an expensive full-range studio monitor but, in this case, they can also be used as a mobile monitor.