It seems you have answered your question, the amp doesn't have enough "drive" to excite the room and engage you as it did in your previous room. I went through the same issue when I moved to a larger room when I was using a 25 watt OTL with the VSM. You just need more power to fulfill what it is you feel missing. This is really subjective from listener to listener but amplifier power seems very much the issue in your case.
