I would go with an Arc, Sub (Gen 3), and two Fives as surrounds. If you have 8-9 foot, flat ceilings, try to sit 7-9 feet from the Arc for the best Atmos listening experience.

“Loud” is often a subjective quality. We humans have been conditioned to equate distorted with loud. With typical audio gear we increase the Volume until the amplifier maxes out and significant distortion begins. This is accepted as “loud”. Going beyond this point can result in system failures. SONOS amplifiers are well protected and in this context will never sound “loud”.

In my college apartment we could operate the system at a level where verbal communication was very difficult, but the sound was clean. Repeatedly, partying listeners would approach, yelling in our ears, demanding “turn it up”, because it didn’t seem “loud”. This same crew, in a different venue, playing a distressingly poor, struggling compact unit, was satisfied that it was playing “loud”. Conversation was easy.

Be sure to include the SUB.

Thanks guys, decision made, arc + sub + one SL’s, sounds great!