Gareth
I suggest you look at "fine tuning" your system rather than making big & expensive changes. This was driven home to me this morning when I replaced the RCA socket with a BNC out for the player here in the office. The difference in the quality of the music was amazing. It now has that goose bump factor much more prevalent than previously.
I hesitate about recommending too much in other directions. Changes you will make can the sound different but "different" does not necessarily equate to "better". However I'm a great fan of electrostatic speakers and have not been impressed with the Meridian digital efforts I've heard. But exposure to those has been very limited so that opinion may not be well founded.
Please go slowly and carefully. Do a lot of net research and try to avoid getting carried away with clever salesmen who (if they are doing their job) make a friend of you and gain your implicit trust. Also beware of enthusiastic amateur posters - we all can get very carried away with new toys and this often deflates over time.
There are many excellent products out there and the Meridian 800 is among them. It is not perfect - nothing is. But take a deep breath and avoid getting on the "upgrade" merry go round because, like that merry go round, you rotate rather than progressing upwards and might even fall off!
John