it all depends on the size of your room. if you have a 13 x 13 x 8 ft room, a pair of mani's would generate enough bass. if you are talkng about a 13 x 24ft room, then you will need a sub. there is plenty of bass but the room will dictate how it will perform. as for subs, i used the rel with my model 1's and didn't use a crossover for the speakers, i let them run full range (as i do my mani's) and i used a 50hz crossover on the sub.
as for your arc driving the mani's, especially if you want a solid bottom end sound, it is too small. i had a 100 watt mcintosh amp hooked up to both my model 1's when i had them and then the mani's and it was not a good fit. my 200 watt classe does a very good job with the mani's and more would even be better. the other option is to use a sub and crossover at 40 or 50hz at the mani's so your amp doesn't need all that power to drive the woofers.
good luck!
as for your arc driving the mani's, especially if you want a solid bottom end sound, it is too small. i had a 100 watt mcintosh amp hooked up to both my model 1's when i had them and then the mani's and it was not a good fit. my 200 watt classe does a very good job with the mani's and more would even be better. the other option is to use a sub and crossover at 40 or 50hz at the mani's so your amp doesn't need all that power to drive the woofers.
good luck!