The Caspian system itself almost definitely will not be the problem (unless they are faulty in some way). I have heard these several times in different locations and situations and they have never sounded as you describe. They are a quality british product and will not have been designed to sound anything less than great! There are however, many things that can, and will, influence the way they sound. Many of these things have already been discussed here.
Firstly, please try to seek the advice of a trusted knowledgable dealer on where things may be going wrong.
Personally I would not think the speakers would be a problem either. Again, in isolation, they will have a sonic signature of some description, but again generally they will perform well to a vast degree otherwise they just wouldn't sell. In some very limited cases, the electrics just won't gel with the speakers but in most cases, neither of these designs are going to stand out to me as being the culprit.
Where things are most likely going to fall down is the setup. I would consider the follow first before giving up and box/speaker swapping:
1. Cables - Avoid fancy all singing/dancing designs and stick to a decent quality copper only cable and connectors. Avoid silver designs, this would most likely heighten the issues you raise. When organising cables at the rear of your equipment, try and arrange them so signal and power cables do not run together. If they have to run nearby each other, try to arrange them so they cross at right angles, rather than sit alongside each other.
2. Stands. Do not stack your equipment items on top of each other, give them a shelf of their own and a little space to breath. Avoid metal and glass construction racks if you are experiencing shrill/glassy high end. Try and obtain some isolation shelving, or stand the equipment on some isolation cones/products to prevent any mechanical vibration adding to the issues.
3. Continue with the soft furnishing thing, try rugs on the wall behind your listening position if you can and experiment, you may be surprised. Whilst you may not want to live with some of these ideas, you may at least identify a issue which could be solved and then find something to work around it.
The equipment you have is worthy of spending the time trying to get it right. Less resolving equipment may not be as receptive to these tweaks, but one thing I have found over the years is that as you get further up the quality equipment chain, the equipment is less "plonk and play" and it starts to demand proper set up to get the best.
Don't give up just yet, and try to beg, borrow etc to try some of these ideas out; so you're not just constantly spending money trying to resolve things.
Best of luck!