beginner seperate system

I wouldn't consider an Atma-Sphere amp for Focal speakers. Ralph is a great guy, but he designs amps intended to drive benign, sensitive speakers. 948's are moderately sensitive, but NOT benign. 
Tubes, for power amplification, aren't going to make those speakers do what they should. If you're looking for a good tube sound, aim for a simple single ended pre-amp and pipe that into a solid state class A amp that smirks mockingly at 2.5 ohms. 

Actually, Atma amps are pretty stable for a tube amp. If impedance drops are severe, he recommends using the Zero Autoformers.
Even Steve McCormack says they make his SS amps sound better.
Bob

Hi dcevens,
As for your concern about Don's preamp, if Don should meet with some tragic circumstance after you bought a preamp from him, Roy Muttram, and Bob Latino are loosely connected with him, so I am sure that they would help, but frankly his gear is well built, he doesn't have a lot of issues or else his reputation would be shot. Beyond that, there are plenty of people who have worked with tube gear for years and would be quite capable of repairing his gear if needs be. The ONLY real problems would be parts as he is using transformers and output capacitors from Europe so there would be a time lag as neither currently have US distribution yet.

I didn't do a good job of proofing my original post, when buying tubes, I go through Don, not Roy. Don uses the best new production tubes, some of which are better sounding than NOS tubes. Roy uses lower end tubes IME. Roy designs rock solid gear, but Don Sachs makes improvements in the circuits at times, and he absolutely uses fantastic sounding components.

The Schiit Freya doesn't seem "colored" in my system, although every preamp has its own sound (I've owned several). In the passive mode you can see this for yourself, unless of course that's colored also...I use NOS RCAs and Sylvanias and the results are excellent, and NOS versions are readily available at a reasonable price (new Tung Sol 6SN7GTBs are also cheapish, and seem to work fine)...it's worthwhile to note that a Don Sachs preamp with remote is nearly 3 times the cost of a Freya, and although it's a  well regarded thing it's just not comparable to a Freya in either cost or features. Also, you can easily make your own REL cables with Speakon plugs and whatever spades or bananas you need, saving some bucks there (I use Canare Star Quad wire for these), and my 2 used RELs were found on Ebay for about 200 bucks each...they work perfectly. I "stack" the REL cable spades on the amp posts, and use bananas for the main speaker wire...works for me.