Under 1500$ Solid State Amp for Usher Be-718

I don't think Musical Fidelity is considered a warm sounding amp. At least this is my experience with their onlder gear. I have not heard their newer stuff.
The Usher amp does, in my opinion, have a very good sense of midrange warmth and does quite wel with the Usher 718 speakers.
Any of the amplifiers mentioned would work just fine with these speakers.

There's only one way to get a tube like presentation and that's with tubes. Some solid state amps, such as the Usher, are a but warmer in comparison to other solid state counterparts. The biggest difference in in harmonics where solid state cannot give you the same 'tone' as tubes.

The Usher amp is very smooth with excellent dynamic control. One of many good options.