Why not try it, maybe a tubed pre or a good passive pre, Both should give you a little spice in your life. Your amp and speakers are good enough for the upgrade.
I spent lots of time integrating a 2 channel system with a HT multichannel system. My goal was to completely preserve the 2 channel path that I had worked to achieve. Basically, the front left and right outputs from an EAD theatermaster pro are output to one of the inputs a Placette dual mono preamp. My two channel sources are routed directly to the preamp. I've seen lots of people mess up a great 2 channel setup when the combine it with home theater. I recommend keeping the 2 channel path as clean as possible.