Atmasphere MA II.2 has been reviewed in the absolute sound driving Genesis 350 SE with good results the review is available online somewhere? never heard them myself. They're more expense than your indicated budget although. Would suggest VTL 450 signature the latest most current version with infini caps I actually preferred my not current version 450 to the Walcott presence amps I also previously owned especially using VTL in triode the newer version is much improved by the infini caps. The Walcott is little more difficult matching your system synergy as its less forgiving of cable matching issues than the VTL is.
your cello may sound excellent definitely try it.
your cello may sound excellent definitely try it.