I have a suggestion.
One 'trick' you could try, is to connect a resistor (initially a variable one, perhaps 50K ohm) between the two loops, across the dipole input.
This will shunt the dipole input impedance and reduce the LF gain. The exact amount will depend on the resistor value. However, it will affect the higher frequency bands much less than the LF bands, and it will not affect the performance when used in loop mode.
Once you have found a suitable value, you can replace it with a fixed resistor wired inside the amplifier case.
I'd anticipate that a value of somewhere in the region of 1k ohm, is likely to be in the ballpark.
Regards,
Martin
