Thank you for your post!
Regarding your query, there isn't anything we can recommend from Bose and I cannot recommend a product from a third party.
I encourage the community to chime in here with any advice.
May 23, 2020
You might check out the DeerCreek 901 EQ. Their idea is to bring these old EQs into the 21st., adding an input switcher that most people use the receivers for.
I don't have one myself, but when I was getting my EQ rebuilt by Rain City Audio, I asked him about them and he said that he had purchased one for testing. It wasn't perfect he said, but it was pretty close. Nothing can beat the original.
Anyway, these (and the original EQs. really) can be run in-line between your device and the amp, or used between a pre-amp and an power amp.
...but this also works:
DEVICE ----> EQ -----> AMPLIFIER ----> SPEAKER
The latter eliminates the ability for multi-device handing, but will work.