I have not heard the Regas yet but will be soon, they are top of my short list because, sensitive so do not need high volumes to drive, can be placed fairly close to a wall and from what I have heard they are very musical. So the 603 should not have a problem with them. As for the totems I don't know them, look at the sensitivity first.
Ok the totems sensitivity is around 87 db so that is lower than the regas which I believe is around 90 db. A demo is needed to hear them as with any hifi, don't just go by reviews use your own ears that is what will be hearing them.