Another amp in this price range to A/B with the Merrill is the new Totaldac AMP-1....($20K for single rca input amp and $40K for XLR mono blocks). Naturally the XLR mono blocks would be the ONLY way to go. I am pretty sure the zero feedback tube/solid state output Totaldac would be more rich sounding but as detailed? He developed the amp using the Magico M6 and high sensitivity horns. Nothing but raves, so far.
http://www.totaldac.com/amp-1-en.htm
Some have said the Audionet Heisenberg amps (over $100K) are the best solid state amps they have heard. Of course, the monster DAgostino amps are killer....back and wallet killers for sure!. Then you have the big latest mono Sim Audio, Classe, FM Acoustics, VAC tube amps, Hegel Reference, etc, etc.
If an amp has a fuse or many fuses then they must all be upgraded to super fuses or the results will be not right. Also, if you have a solid state amp that has heatsinks and you do not dampen the heatsinks (easy to do)....then you are hearing the ringing of the heatsinks. If you run your fingernail along the heatsinks and it "zings".....then you are adding that sound to the output......very important to get rid of that ringing. From pics I can see the Soulution and the CH precision both have ringing heatsinks (bad for sound). They would sound much more natural with heatsinks damped.... Totaldac amp has lots of ringing heatsinks.