Totem and Bel Canto?

"but the Arros are indeed easy to drive"

PErhaps to drive in general, but do not let the small size fool you. To drive optimally for best balance and performance, I believe they require significant power and current. They are fine speakers especially for their size but I would not categorize them as "easy to drive"

Like your friend I am using an Arcam avr400 with my Totem "The ones" I'm using the Mites as surround and a Model one signature as center as well as a Jl Audio f113 sub (wich I love)
I'm very happy with the Arcam avr400 its very powerful real 90 wpc drives the whole thing easily with power to spare and the sound produced by the Arcam combined with Totem speakers is awsome.
The dealer I got it from had the Totem Forest set up with the Arcam avr400 thats what sold me.
My family room is 20x20x12 sloping ceiling as high as 16 feet on an open floor plan, thats a pretty big room (one of the reasons I got the Jl Audio sub) but the Totem monitors project very big sound and dissapear beautifully.
I dont feel that I'm missing anything the mids and highs are clear and as far as low octaves are concerned the Jl audio sub does a fantastic job, it takes a while to get the intergration of the sub to work to my satisfaction has been about two months and still working on it.
Good luck

The Arros aren't impossible to drive, but I wouldn't call them easy by any means. They've got an odd impedence load that requires a stable power supply. You don't need kilowatts to open them up, but you do need an amp that doesn't have difficulty delivering current into 4 ohms and less. Not sure what they actually dip down to, but I'm pretty sure it's less than 4 ohms. If impedence isn't the issue, phase angle may very well be.

A Nait 5i has a power supply that'll take care of them.

The Rainmakers and Arros are pretty similar. Totem doesn't design lines per se (as in B&W 683, 684, 685). Every speaker is it's own individual speaker. However, the Arros and Rainmakers are quite often paired up together in surround applications. Same can be said for the Sttaf and Mites. I think the Arros and Rainmakers use the same driver, but different tweeter. Sttaf and Mite is most likely the same thing.

Just a heads up on Totem in general.

I have owned the NAD T747 and although my current Bel Canto DAC and Amp combination was per-dated by some other components I can offer two opinions. First, the Bel Canto should blow away your current NAD as it did with mine with both Focal and Dynaudio Speakers. Second, I would highly recommend the newer Bel Canto C5i overe the older, less featured S300iuas I believe it to have a better amp section and a substantially better DAC.

I have bel Canto 2.7 DAC / peramp and a REF500S power amplifier hooked up to a pair of Totem Sky Towers and the imaging is beautiful along with a great sound stage. Compared to another set of speakers I have that don't produce the same amount of bass even though they are bigger Focal 826.. The Focal  are more sensitive but drop to 2.6ohms and are diffucult to drive in the bass regions ' they roll off considerably and need a sub. Whereas the Totem only drop to around 5 ohms and don't really need a sub in a small to medium room. The Totem has aa bigger and fatter presentation than the Focal that just sounds right. The Focal in fairness are a lot cheaper and do impart a house sound that has lots of space around the upper mids and Treble. The Totem are more addictive though in my view.