I am reading a mixing tutorial book that suggests regularly switching back and forth between your stereo nearfield monitors and a single mono Avantone Mixcube to tune your mix.
I have a ProFire 2626 and mix ITB so I have plenty of additional outputs. How would I configure my routing so I can swap between these at the touch of a software button within Cubase? I have the full Cubase 6 but haven’t ever used control room or routing features.
Have a closer look at the control room 
That’s good advice, but there’s no reason to actually listen to a single speaker… Just summing the L & R channels to one mono signal should be sufficient, whether that signal goes to one or two speakers. Can’t help you on routing since I have a simple ‘mono’ button on my DM3200.
Luck, Arjan
The point of the avantone mixcube + mono together is to deal with a lot of small studio mixing issues, not just checking mono compatibility. The mixcube is a single-driver system that is very focused on midrange. According to the book, this allows you to focus on the most important part of the mix, while nullifying a few major problems–room modes (not enough bass in the mixcube), phase issues (single driver), etc.
Try these. Assistance vfom Split in the 1st link, and from vic_france in the 2nd. How much better can it get? 
Split is right! Control room is your friend here. Just add a mono monitor channel and connect it to one of your outputs.
Sweet. I’m all set up. Tell me if I did this right.
I don’t have the Mixcube yet. But I pulled up the ProFire 2626 control panel and verified pressing F1 sends signal to my stereo monitors (which I can hear of course) and pressing F2 sends a mono signal to SW return 3, which is mapped to an analog out that will… soon… have an Avantone Mixcube attached 
NS10’s (dare I say it) are good for that sort of thing too! (obviously in stereo though)
Looks like you made it.
NS10’s are indeed good for this also. In my opinion most important thing is to have (at least) 2 sets of monitors with different sound on your system.
Yes, that’s where my NS10s come in the picture as well. Both in mono and stereo.
Luck, Arjan
I always audition in my car and lately on my iphone speaker! Also sometimes through my PC monitor speakers. I’ve not found a way to connect my car up to the control room 
Mike.
I’ve had NS10s as 2nd or third monitors for decades, they do push the mid a lot and lack bottom but the mid clarity is second to none.
Also dont forget the room treatment, just being redoing mine and it does bring home just how important it is. Ye canny have too much LF absorption
Yes I am going crazy with the room treatment right now: 8 panel bass traps plus several floor-to-ceiling 2 foot deep soffits designed to soak up anything below 80Hz. And plenty of high frequency absorption to reduce flutter and comb filtering.
My insulation supply store knows me by name now 
Easy! Make a big enough door in the wall of your control room so you can drive the car in 
That’s the bizz Don’t forget your primary reflection points. (not that it sounds like you will) 
Easier: Buy an FM transmitter and put your mix on. In the car; select the frequency and enjoy! Or, tweak a little more and then enjoy! (You wouldn’t be the first to practice this, BTW…)
Luck, Arjan
Well, my studio is in the basement room right next to the garage, but hooking my car stereo to the control room might result in either a dead battery or carbon monoxide poisoning…
Just like you, I also have cheap earbuds (as well as high-end headphones) connected up to my interface too… but I think where the mixcube comes in is that you can quickly switch between that and your nearfields to get another perspective without having to burn a mix.
The book also suggested that your ears adapt to whatever environment/speakers you’re in which is a double-edged sword. It’s good because if you have unavoidable issues with your room or monitors that you can’t fix, your ears can correct for them. It’s bad because if you listen to a mix too long on the same monitors, you adjust to problems you introduce in the mix too… so quickly and regularly swapping back and forth between different monitors helps. I’m sure this is where the NS10s come in handy, but the Mixcube solves that problem, plus the phase/room problems, plus the mono problem all in one.
Now if I could just figure out where to put it…
Portrait aspect… interesting
I’d put it on a pole so it sits above the middle of the two monitors.
I had them landscape but it spread my stereo field too wide. As they sit now I have an equilateral triangle between my head and the two tweeters. It would be more ideal to stack them vertically and keep them landscape, but the monitor mounts wouln’t allow me to get the bottom monitor all the way down to the desk so the top one was uncomfortably high.
There actually is a pole back there for the monitor mount. It can be extended but I need to figure out why contraption would safely hold the mixcube.
I’m juggling the same kind of problem at the moment, I’m wanting to put in two new wide screens but don’t want to have my primary speakers to wide either. Hmm, what to do?
Could you not fix a mounting to the back wall?