LS 26 audio research Gain Settings

I want to know why, when I adjust the Gain on my preamp, that the sound is louder, whereas on the technical data, there seems to be less voltage on the High Gain than on the Low Gain. Second question: Does anyone know how the gain control works, is that on the High Gain the sound is more direct and consequently, on the Med Gain and Low Gain there may be resistors or other electronic components which cause the sound to drop? I also noticed that at High Gain, the average listening volume is 9/104 on the volume control, and that the maximum is around 20, and that I notice a kind of saturation in the music. On the other hand, if I select Low Gain, I can increase the volume to 55/104, 104 is the maximum volume reached. I also noticed a lot more dynamics in High Gain mode, but more stability in Low Gain mode. Can you explain to me the difference, when I select the Gain on my LS 26, between the In Put and Out Put values ​​"A- and B-" Thank you for your help. LS 26 preamp specifications
FREQUENCY RESPONSE: + 0-3dB, 0.2Hz to 160kHz at
rated output (Balanced, 200k ohms load)
DISTORTION: Less than .01% at 2V RMS BAL output.
A- GAIN: Main output: Selectable for each input: 24dB, 18dB,
12dB Balanced output. (18dB, 12dB, 6dB SE output.)
Record output: 0dB (Processor input: 0dB balanced).
INPUT IMPEDANCE: 120K ohms Balanced, 60K ohms SE.
Inputs (8): Tuner, Phono, CD, Video, Aux 1, Aux 2, Monitor,
Processor (XLR and RCA connectors).
OUTPUT IMPEDANCE: 700 ohms Balanced, 350 ohms SE
Main (2), 20K ohms minimum load and 2000pF maximum
capacitance. Outputs (3): 2 Main, 1 Record (XLR and RCA
connectors).
OUTPUT POLARITY: Non-inverting.
B- MAXIMUM INPUT: Low Gain: 48V RMS BAL, 24V RMS SE,
Medium Gain: 24V RMS BAL, 12V RMS SE, High Gain: 12V
RMS BAL, 6V RMS SE.
RATED OUTPUTS: 2V RMS 1Hz to 100kHz into 200K ohm
balanced load (maximum balanced output capability is 15V
RMS at less than 0.5% THD at 1kHz).