The 18NS is among the finest pre-amplifiers—one benefits greatly from using the pre-amplifier with the 108 in single-ended mode. The same is true when using a DAC with internal volume control. The 18NS has a sophisticated phono pre-amplifier, with recent models updated to accommodate Herve's newest darTZeel low-output moving coil cartridges. All to say, a portion of the 62,000USD price of the 18NS is for its exceptional phono stage. If you are digital-only, perhaps a higher-performance DAC (although I understand the Holo is quite good). I am watching closely the soon-to-be-released Lampizator Posiden, which, in addition to an end-game DAC, incorporates Lukaz's latest pre-amp circuit. US retail is approximately 25k. Two line-level inputs are included.
Enjoy your 108, and have fun with your next step.