Tube amplifier suggestions for the Graham ls6

[Mhswitzer]

I own and like very much the Graham LS6 speakers, which I bought for their rich mid range. I currently use an Atoll in100 solid-state amplifier. I have been thinking about also purchasing a tube amplifier to use with the speakers, and I have two questions: (1) would using a tube amplifier with these speakers be too much of a good thing, i.e., would the sound be too soft or mushy, and (2) if a tube amplifier would pair well, can you suggest any tube amplifiers under, say, $3000 to consider? Thanks.