Understanding the Need for Amplifiers in Hanna pH and Redox Controllers: A Client-Advisor Interaction

Client:
I have a pH controller Hanna BL 931700 and a redox controller BL 932700. I now have a pH probe HI62910 and ORP probe HI62930. At the end of the cable, there are two 3V batteries. I am unsure if these are necessary. Could you tell me if you have a compatible probe and whether they will function without the battery?

Technical Advisor:
Hello, we do not have replacement probes for those versions. I apologize for the inconvenience, but this is due to their amplifier.

Client:
Is the amplifier necessary?

Technical Advisor:
It is better to have it!

Client:
According to the manual of the pH controller, it seems to work with the HI2910B. There is only a 2m cable between. Why is the amplifier needed?

Technical Advisor:
If the manual states that it works with the HI2910B, then it should be okay. Amplifiers are used with some "weak" electronic devices. In your case, for pH, you can check here and for redox, check here.

Client:
Thanks.

Technical Advisor:
You're welcome.