Hi Rod. I'm a big believer in separate amplification. And yes your speakers are harder to operate at 4 & 6ohms ratings.
I never knew what I was missing until I added a 205wpc Parasound amp to my system. Now I will never go back to just using a receiver. All of which usually overstate their specs as far as power goes.
I would suggest getting a 5 channel amp of at least 200wpc. This will ensure that your speakers will operate to their full potential because the power is there whenever they need it. (Which is the most important factor for me.) It's better to have it & not need it rather than need it & not have it.
It will also drive any speakers you get now & in the future since you can keep it through all other upgrades to your system, since power never goes out of style!
Good bang for the buck new amps are Emotiva (XPA-5). Outlaw Audio. You can also look on Audiogon for a used amp from Rotel, Parasound, Sunfire, B & K, Adcom, Nad.
Do it once, do it right, sit back & enjoy for years!