Pass XA Monoblock Amps

I know there have been many threads on these amps and the different levels of power with each set. To those who owned the Pass XA60.5 and went to the Pass XA100.5 monoblocks, did you feel that the change made a big difference in your system or was it not that noticeable whether played at low to mid level volume levels or high volume. I currently own the Pass 60.5 and am contemplating the Pass 100.5. Some people have suggested that it would take a move to the Pass XA160.5 for it to really make a difference but that would unfortunately be out of my price range. The room is 12 by 24 and the speaker load is 2 ten inch seas woofers, 2 seven inch mids, and the tweeter. They are 4 ohm with a sensitivity of 91 but a big speaker. Any thoughts from Pass owners of these amps would be appreciated. The other direction i can go would be to upgrade my Pre-amp from the Rowland Capri but my initial thought was that the Pass amp change would be more of an upgrade. Thanks for your thoughts.