It should work out ... on paper anyway.
The Plinius SA-100 amplifiers have 47 Kohm input impedance, which is theoretically a reasonable match for a passive (Lightspeed, Bent, etc) and hence a reasonable match for source direct.
Also, both the Arcam FMJ CD37 and the Esoteric SA50 have output impedance less than 100 ohms.
Given that your amplifier and your source (current and proposed) are theoretically well matched for a passive setup, you don't need to buy the Esoteric SA50 to accomplish this, a good passive would also do the trick.
However, you may want the Esoteric anyway. Either approach should work out in theory, but proof is in the listening.
If I may interject my own personal bias: with all of that solid state, I'd recommend a tube preamplifier, perhaps a Mapletree Line 2A SE for the budget conscious.
The Plinius SA-100 amplifiers have 47 Kohm input impedance, which is theoretically a reasonable match for a passive (Lightspeed, Bent, etc) and hence a reasonable match for source direct.
Also, both the Arcam FMJ CD37 and the Esoteric SA50 have output impedance less than 100 ohms.
Given that your amplifier and your source (current and proposed) are theoretically well matched for a passive setup, you don't need to buy the Esoteric SA50 to accomplish this, a good passive would also do the trick.
However, you may want the Esoteric anyway. Either approach should work out in theory, but proof is in the listening.
If I may interject my own personal bias: with all of that solid state, I'd recommend a tube preamplifier, perhaps a Mapletree Line 2A SE for the budget conscious.