Preamplifier remplacement

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The suggested preamplifier can be ordered only in few countries, then needs to be modified which includes SMD soldering. The authors say that no ready off-the-shelf preamplifier could be found. I would like to ask, what is so specific about the preamplifier? If it cannot be replaced by, say, this (one of many options):

https://www.kemo-electronic.de/en/Light-Sound/Amplifier-Splitter/Modules/M237-Stereo-Preamplifier.php?faq
9 - 24 V/DC stabilized (or battery) | Current consumption: approx. 3.4 mA ± 20% at 12 V (without load) | Frequency range: approx. 8 Hz - 60 kHz, 3 dB at U out 1.5V RMS | Input impedance: 100k Ω | Output load: > 2k Ω | Amplification: approx. 30 dB ± 20% | Distortion: ≤ 0.02% ± 20%

then what is the exact reason? Noise level? In particular, is the signal inversion of the original amplifier important? If yes, it seems like something easily modifiable in software.