I applaud you for going in-ear.
Sorry but there is no way to directly connect the analog GL2400 to the digital Avioms. Aviom sells an analog to digital converter for that purpose. I do not feel it will be worth it to purchase a converter unless you get a smoking deal on one, like $50 to $80. It will most likely eat up all your GL2400 aux outs. The GL probably does not have 16 aux outputs. I know the GLD series talks directly to the Avioms. Some other mixers in A&H digital line may speak Aviom too, I just don’t know.
Good luck. John