I have a MD90t(unbalanced connection)and it sounds fantastic. I purchased it in 2011 I think. I had considered a few years ago to also purchase a MD107t or a MD108t but never got around to it. I'm quite satisfied with the sonics from my MD90t.
I listen to a lot of radio and have several tuners by McIntosh: MR75, MR78, & a MR7083. I also have a ReVox B780 receiver for analog tape playback and for FM radio. All produce excellent sound.
Moving to the MD90t from your MD100 would be a noticeable and worthwhile improvement. I've not listened to the MD105t however.