The most synergistic preamp for a 23.5 is the ML 26s. (see my system) They don't appear used very often but I think there's one for sale right now on the Gon. .
The Essential preamp was voiced with ML, I think it is one of the best out there. What is your budget? Do you need phono? If you are going only digital a passive Placette would be a good option.
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