I completely understand the rationale for the SL32 inputs: TRS = line-level + no preamp and XLR = mic-level + preamp + possibly phantom power.
However, many active DI or preamps boxes are able to use phantom power when transforming Hi-Z to line-level inputs (e.g. for a bass guitar).
This avoids the need for a PSU for the DI with XLR-XRL cBLING, but of course then we don't need the SL32's preamp.
Cheers,
Yves