Loft as a listening space?

I'm thinking of moving to an apt. with a 25ft cathedral ceiling. It has the typical L shaped living/dining room configuration. I'm considering making the upstairs loft (8x10ft) into the 2ch listening area. Two sides are open - as it hovers over the living/dining room areas. I have monitors and sub. Will this be an audio nightmare or can it be made to work?
It can be made to work, but IMO/IME listening in a nearfield arrangement will work best. If you like a nearfield set-up then it can be great. There are a lot of advantages to this type of set-up.

Smaller speakers required, smaller amp required, less room interaction (certainly in your case).
A nightmare in getting quality sound. Room treatment, which is always necessary in any environment, will be next to impossible at reasonable cost.
Nice space for quality headphone system.
the open 2 sides will play havoc with the stereo balance - you need the walls to the sides of the speakers to be similar if not identical. you might be able to help things enough to be tolerable by building a reflecting panel/wall segment to place at the side of the speaker that lacks a side wall.

(I used to live in a loft space that had this issue, although with different variables than yours)
It will be a great and fulfilling challenge,go for it,cheers,B
By going to a nearfield arrangement, much of what the other posters are stating with regard to the room issues become more mute. The idea of the nearfield set-up is to reduce, restrict or eliminate the room boundaries from the sound. A recording monitoring studio with a nearfield set-up is a good example of this.

Can you eliminate the room, not realistically, but taking this approach properly can get you a long way there. I would not be scared to try this and think that you can get good sound in doing so without killing yourself in the process.
Posting pictures of the space would be of great help. What type of speakers and sub are you going to use? How loud do you like to listen? It could be a great space. It's hard to make any intelligent response without more info.
Thanks for the feedback. I'll try to remember to take pictures next time I'm there. Nearfield listening could do the trick. The speakers are Acoustic Zen Adagio Jrs along with a Talon Roc 2002 sub.
I don't know how some of you can predict such dire results with so little information. I'd just try it.
My one home had a huge room like that,22x30x24' high?. Ballpark, it was big enough to fit a small ranch in it. I couldn't use it for my main listening room do to the echo. I ended using small monitors that I could aim directly at me. This helped cover a lot of the echo characteristics it had. The next time your there, have someone talk loud in different spots. Go to where your listening area would be, and have them go to your speaker placement area. Their voice echo should give you a starter of an idea of what you may be up against. Maybe a portable boom-box, with loud vocals that would echo. Keep in mind that it's expensive to heat a home like that, unless you stay in the upper area where the heat rises to. AC was less staying in the low area. I liked that home the best, but not up to a ~5000 (sq.ft.) home anymore.
With those speakers, a nearfield set-up could be very nice. Not sure how your sub will integrate though. Since it is not a point source, you may find the sub to be the problem. Although, you may also find that the sub isn't necessary in this arrangement - try it both with and without the sub turned on or connected. The sub, I think will either become over bearing as it will try to fill the room and then feel slow and sluggish due to the room size. On the other hand, if you keep it toned way down, it may get lost altogether in this space. I would even be tempted when playing with the sub to place it closer to you, perhaps just behind you, keeping it toned down. By having it closer, you may be able to lessen the volume of your space be getting a more direct impact from it. By having it just behind you, may also expand the soundstage to the rear to some degree (I know this isn't exactly natural for a set-up), but I once listened to a friends Martin Logan Summit set-up and he added a sub to the back of the room. The affect was pretty nice - albeit a completely different setup that the OPs.
I use a loft as a office listening space I just use massive horns which do not negatively react to the space.
Here's a bad word that could be just what the doctor ordered in a case where the room is just too far gone to address things otherwise. Don't tell anyone here I used these words:

-graphic (or parametric) equalizer

Nearfield listening is another practical approach.
I like the idea of horns for when you may want to fill the space.

You might also look into omni solutions like those offered by holistic audio. Not sure if your space is too big for what they offer, but they sounded great at a chicago audio society meeting. From anywhere in the room, including standing against the walls. I'd contact Jack to hear his thoughts.
"You might also look into omni solutions like those offered by holistic audio."

Not a bad idea.

The Holistic audio speakers advertise a quasi Walsh omni driver.

I can dig that!
Steakster, so have you played around with anything yet? We'd be glad to hear your results and what you found worked best for you. And of course, what proved "fatal".