I've gotten most synaesthesia (crossing over of senses) with mushrooms and LSD, but also with 2C-B + nitrous.
LSD: first time I did it, I could taste the color blue and I realized it was not only my favorite color but also favorite color-word lol. It was pretty strange! My dad took me for a car ride
after that and I saw beautiful velvety pastels. Awesome
Mushrooms: first time I did that I closed my eyes when music was playing and I completely
visualized the music as if it were a vision. Like an auditory landscape, there is no explaining it in any other way...
2C-B + nitrous: with this combo I got stuff like I felt the color red being applied to the top- and rightside of my brain, it was tingly and kind of like a concept instead of a substance,
in this case a color, enveloped it and almost gently kindled it!
:D good stuff! But in no way ontopic I suddenly realize lol