That will be an interesting switch from the L810's to a small monitor of recent design. Very different sound I think, and if you get a brightish sounding amp to go with the L810's, you may regret it.
Better to find an amp that will mate well with the speakers you intend to buy. As a suggestion, there's an Electrocompaniet ECI3 advertised by jeffsoundvalues on AudioShopper.com today that would probably be a good fit for the Merlins. I've never done business with them but have spoken to them and they are very helpful nice guys with what seem like fair prices. They should be able to steer you in the right direction.
Bottom line though, settle on the speakers you intend to keep before trying to find a matching amplifier.