Tā duì yīnyuè rúzuì-rúchī, měitiān liàn qín liù xiǎoshí.
He's so mesmerized by music that he practices piano six hours a day.
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usage
The variant 如痴如醉 is equally common - the order of 痴 and 醉 can be swapped. Both describe total absorption in something beautiful, typically art, music, or scenery.