Is he buying this himself or are you purchasing it for him? If it's the former just get him to buy a Fishman of his own, problem sorted. Seeing as you already have PA and monitoring an amp is a bit pointless IMO.
If funds won't stretch to a Fishman then this might work, still has a notch filter for mid set feedback busting and is only £36 with the BLACKFRI20 code.
https://www.ebay.co.uk/itm/315171151745
Does have a 10 megaohm impedance but no mid freq and a single treble control, you can dial out piezo quack and harsh high end at the desk though.