stereo5"It will be hard to find an amp to tame the highs in your speaker."
It will be easy to improve the high frequency performance of you're speaker if you engage the support of a good dealer who is willing to loan you on approval an amplifier that he thinks might be better than you're Marantz which would not be hard to do! If you do not like the first loaner I would suggest, recommend, and encourage you to try another amplifier from you're dealer who should be willing to help you this is one of the basic roles of a true, expert, committed high fidelity dealer and this should be you're next steps rather than replacing you're speakers which is a substantial, significant, major step and irreversible.
It will be easy to improve the high frequency performance of you're speaker if you engage the support of a good dealer who is willing to loan you on approval an amplifier that he thinks might be better than you're Marantz which would not be hard to do! If you do not like the first loaner I would suggest, recommend, and encourage you to try another amplifier from you're dealer who should be willing to help you this is one of the basic roles of a true, expert, committed high fidelity dealer and this should be you're next steps rather than replacing you're speakers which is a substantial, significant, major step and irreversible.