I don't think it's synaethesia: synaesthesia is the crossing over of two sensory modalities (e.g sound and colour, letters and colour, sound and taste, etc.) so that when one stimulus is experienced, (e.g a letter) a second entirely internal perception (e.g colour) is triggered, and the synaesthete sees the letter as inherently coloured automatically whenever they look at it. I have grapheme (letter) colour synaesthesia, but it never triggers an inherent emotional response.
What the OP is describing sounds like the sensory differences which occur in autism; Ryan, it sounds like you are hyposensitive to specific stimuli, and crave more of it or at higher intensities than normal people, and experiencing said stimuli causes a pleasant or euphoric feeling. I get the same feeling when I look at rapidly flashing coloured lights, like Christmas lights, or those flashing bouncy balls which light up when dropped. I also get hooked on certain textures, and find myself stuck in clothing stores, unable to stop stroking specific clothing items, compelled to feel them with my face as well as my hands, as the face is more sensitive to touch.
_________________
"Survival is insufficient" - Seven of Nine
Diagnosed with ASD level 1 on the 10th of April, 2014
Rediagnosed with ASD level 2 on the 4th of May, 2019
Thanks to Olympiadis for my fantastic avatar!