Although not the last word, those Hitachi amps were pretty gutsy from what I remember.
I'd advise against those Epos floorstanders with a micro unit. They are simply going to highlight any shortcomings in the electronics. The Yammy is a cracking little box of tricks but, like most of those systems, has its limitations.
My Dad has a TEAC Reference 300 system and originally had it partnered with Quad 11Ls. That was overkill in the same way and it never sounded right. He changed to Tannoy Custom F1s and it sounds magnificent because the synergy is better and the speakers complement the electronics rather than shining a light on their weaknesses.
Instead, if the Tannoys or Cambridge S30s aren't going to fit your bass requirements, I'd be tempted to go down the 2.1 route and add an active sub. At least then you will have control over the bass but won't be over stretching the Yamaha.