Maggie 1.6's and Power. How much is enough?

Wattage ratings alone do not tell the whole story. However, your Marantz at 120 watts is not "way too small" for the Maggie 1.6s. Generally, the Maggies need an amp the will drive a 4 ohm load. The best values would be a solid state amp like the Marsh A-400 or BAT VK200. Tubes will work but you need at least 100 watts.

While the Maggies will work in a H/T setup, they may not be the best choice for a "smaller room." Not only will they visually dominate a smaller room, the speakers sound best when they are at least 3' from the front wall with the listening position at least 6' away. More importantly, is that the Maggies project a small sweet spot and sound best in a high quality 2-channel setup; the Maggies forte' is soundstaging. Consider that there will be a discontinuity between the center channel and the Maggies. Consider, also, that in a H/T setup, a conventional cone speaker will sound more dynamic and will resolve more low level details at lower volume levels.

Does your reciever have amp out jacks?If it does you could add Marantz monoblocks or a stereo amp to power the Maggies.I had the Maggies and i think they need about 200 watts a channel just for themselves.

Your power will be slightly lacking for demanding HT and music listening. tireguy is correct about the center channel. you'll need to do a fair amount of channel level setting to get an acceptable blend up front. There are Maggie centers but the are fairly large and quite power hungry too. I you do decide to upgrade to another power amp, for minimal cash, try to find an Acurus 200X3 for the front. That amp (as well as other Acurus amps) can handle difficult speakers like the Maggies very well. For the money, they CANNOT be beat. And there resale is excellent if you don't like their sound. good luck!!!!:)

Try a McCormack DNA-1 or 2. I agree with the above poster that mentioned Marsh or BAT. You need a musical amp with great current drive. I never heard the Krells with the maggies but would imagine it would have glorious sound as well. Ditch the Marantz idea.

In a small room you will probably have enough power for most of the time. I think the bigger problem is the smaller room. These speakers sound their best when you get at least 10 feet away, 12-15 feet is better, and they like to be far away from the walls as well. My room is 13 x 20 and just big enough for me.
They are excellent speakers and will sound better and better as you improve your system.