Since you plan to use your integrated amp's pre-amp section, the answer for your last question is YES.
I cannot answer if your MH preamp is better or power amp section is better. Previous owners or that amp who have experimented can answer that. Or take your amp to a dealer of the power amp and do a test in his system.
I had done the same thing with my NAD integrated. But I had used it's power amp section and replaced the preamp with a TVC. Eventually sold the amp and have the current config. Good Luck.
I cannot answer if your MH preamp is better or power amp section is better. Previous owners or that amp who have experimented can answer that. Or take your amp to a dealer of the power amp and do a test in his system.
I had done the same thing with my NAD integrated. But I had used it's power amp section and replaced the preamp with a TVC. Eventually sold the amp and have the current config. Good Luck.