I don't see it as an amp problem but a room configuration problem. I do not know if an amp change will overcome distance to the listener and speaker separtion.
I have integrated my two channel into my home theatre. It is not optimum for the HT but good and great for the two channel.
Have you tried swapping the HT and two channel systems? Distance would be less critical with the HT. Swap the chairs and sofa also if needed. Get rid of the coffee table-refections off it must be terrible.