@wlutke The N200 presents sonics in a very linear, neutral way with lots of snap and dynamics. As a dealer that has had one on my floor for years, I have not heard it be grainy, but you also do get considerably more tonal richness and organic presentation in stepping up to the N20. That said, I believe the N200 is one of the best value propositions in the Aurender line, as with the rest of high end audio, diminishing returns are evident the higher up you go.
My suggestion would be to work with a dealer that can offer you an upgrade program, such that they will take the unit back in trade if after some time you want to jump up to the N20.
One other suggestion, having had a lot of experience with many of the components in your system, is to try different tubes in your Audio Mirror DAC. NOS Telefunken, despite their high reputation, deliver a hotter, more overdriven sound (not really overdriven, but very textured and gritty at times), that many people crave. The Audio Mirror itself is a very neutral DAC (Vlad is a close friend of mine and lives fairly close by), so perhaps try some 6922 variants that have a sweeter tone.