https://www.amazon.com/gp/product/B08NJS5FV8/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
Or if you need multiple inputs:
https://www.sweetwater.com/store/detail/MIDImerge2--midi-solutions-multivoltage-merger-2-in-1-out-midi-merge-box
Or if you want to go big:
https://conductivelabs.com/