I've got a fully restored SA-9100 and absolutely love how it sounds. It also makes a fantastic headphone amp. My primary LCD-3 rig is Gungnir->SA-9100->LCD-3.
One thing to keep in mind... the SA-8100/SA-9100 are almost 40 years old. No matter how functional it is, if it hasn't been re-capped, it most likely needs to be. There are also some known flaky transistors in these that should be replaced, since 90% of the work is getting to them and the boards would already be out for re-capping. On the up-side, it's totally worth restoring, especially if it's cosmetically good and you can get it for a decent price.
I'm running a very similar set up :)
Gungnir ---> SA-9900 ---> Hifiman HE-6 and Fully Modded Magnepan SMGa (mods done by me. Pic of one of them below)