Are you going to disconnect/reconnect speaker wires between HT and music? There are other options.
-a tubed pre with HT bypass (you want unity gain, with ability to bypass while off, so as not to imbue sonic signature during HT playback).
-if you really want a diff amp, you may try an integrated with HT pass-thru.
My thoughts: I am no longer entertaining these ideas, but I had researched them a bit recently. Far and wide where I asked for opinions, most said to upgrade the pre/pro rather than the amp. It might be very possible that your amp upgrade might become more of a lateral move than a truly discernable upgrade if you are using Emotiva. Depending on some other factors too, but still.
But even more that the pre vs amp... you are considering a great deal of money, when combining TWO pre-amps, and TWO amps, but have only invested $325 in speakers?? Im not trying to step on your toes, but rather understand where you are coming from. To spend on the speakers first is one of the few things that nearly all would recommend!
What are your other speakers, if any in possession? Perhaps save money for a while, helped by not buying yet another pre and amplifier, and getting some
even better BWs for the fronts, and pushing the 602s to surrounds? Maybe some CMs.

Penny for your thoughts...