If the ratio is good between preamp and amplifier this device will add nothing
Some here agree with that statement but others of us hear it differently. A buffer should not be needed if you use an active preamp. The need for buffers came about from the use of passive volume controls (or passive preamps) and from DAC-direct solutions where the DAC contains an internal volume control and can be directly connected to the amplifier(s). Those who use buffers typically report similar results to what you hear, with more tonal color and depth, better bass, and an overall more robust sound.
Contact Placette on how best to address your battery issue, or whether you might add a LPS to power the unit.