well i've never had any experince with them, but i've read on other forums that they are great sq amps, didn't hear much about them being underrated much though.
th older xtant amps were crazy and still are. Very nice and very good. The new ones are high end Mitex( or whatever MTX parent company is) and they do well but I don't feel they're like the older ones. They took away some of the EQ features but they're still udnerrated for sure.