Paul (OP not AK),
Nice to see another Edinburger on the forums! Some day we shall have to gather together all of our kind doon the pub and compare hifi stories.
As for your upgrade plans... I would be tempted to follow the advice of a few members already and get yourself some quality stands for your speakers. It makes a rather shocking amount of difference.
The next thing I would do if I had a wad of cash burning a hole in my pocket would be to have a listen to all the speakers in my price range that I like the look of (and that might work well with my amp and room). As I don't have much experience of valve amps, I couldn't really recommend anything useful (my usual recommendation is something from the ATC stable - the SCM-12s at £999 are fabulous - but 12-watts of valve amplification may not really be the best match for them... that said, I've heard a pair of 12s driven by a medium-wattage valve amp and as long as you didn't crank it to crazy levels it sounded rather wonderful.)
As for where to go in Edinburgh, you really need to go see Graeme at Retro Reproductions down on Leith Walk (28A Haddington Place). He's a one-man hifi dealer specialising in used hifi, though he does do a few brands new (including ATC). He's also a bit of a vinyl/valve aficionado and I'm sure can offer you advice on your predicament. He also has lots of cool hifi bits and bobs lining the walls of his shop so it's always interesting to pop in just to see what he's got his hands on at any given moment. Furthermore, by virtue of his almost exclusive dealings in secondhand kit, he's always happy to give you a home dem.
Other than Retro, your best bet is probably Loud & Clear. The rest of the hifi shops (Hifi Corner, Sevenoaks, James-Morrow) are alright, but pretty mainstream and it can be hard finding someone who knows what they're talking about.
Another idea would be to try Glasgow. There's a wide variety of hifi shops in Weegieland and you should be able to find someone who can help you out. Let me know if you need any recommendations. (Oh, and there's always AnalogueKid and The Devil if you need Glasgow guidance.

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Dunc