Solid state amplifiers always sounded lean on my Martin Logan CLS, but any tube amplifier sounded great. After trying numerous solid state amplifiers I decided the problem was the speaker's wicked impedance curve.
The CLS has very low impedance in the upper fequencies and when solid state amplifiers see a low impedance, what do they do? They produce more power. Also, the CLS has very high impedance in the low frequencies where the solid state amplifiers would produce less power.
More power to high frequencies and less power to low frequencies made for a very lean sound.
Tube amplifiers didn't seem to care providing the wattage was high enough.