Thanks to everyone for their the advice. This morning I listened to four sets of speakers with the Arcam Solo Mini at Bartletts Hi-Fi.
My test CDs were from Radiohead, Panic! At The Disco, Mozart, Boards of Canada and the Beatles. The speaker cabling was Atlas (don't recall the exact type). This was my first time listening to hi-fi equipment in a demo room, so I wasn't sure what to expect.
I started with the Dali Lector 1s and was frankly disappointed. They are obviously cheaper than the others and OK Computer isn't the easiest thing to play, but they sounded really mushy and disorganised. Other tracks weren't much better. The percussion wasn't sharp and voices sounded flat.
The second set of speakers I tried were the AVI Neutron 5s. They were definitely more listenable than the Dalis, but I still wasn't happy. On the Mozart piano concerto the orchestra was still muddled. Voices sounded somewhat hollow on all the tracks. I was rather disheartened at this point, other forum members had rated them, perhaps I was expecting too much from the Arcam?
Third up were the PMC DB1is. To get to the point immediately: wow. When playing the Mozart piano concerto I could clearly hear where each instrument was positioned. The DB1is remained organised when playing Airbag from OK Computer (a tall order) and guitars on the Panic track sounded like they were in the room. Listening to Back in the USSR and Dear Prudence on the White Album brought a smile to my face. The sound was very involving and detailed yet still warm. The bass was clearly the best of the four. I could have listened all day.
Finally I gave the Leema Xeros a listen. They made Boards of Canada's Aquarius sound wonderfully smooth. However, despite being better organised than the Dalis or the AVIs they were too laid back for me. The Mozart was good, but I wasn't drawn into the music like I was with the PMCs. There wasn't enough excitement and bite.
In conclusion it's got to be the PMCs for me. They sounded awesome. The Leemas were good too, but not in the same league. Neither the AVIs nor the Dalis impressed me.
Couple of final thoughts. The difference between the speakers was much larger than I expected. The law of diminishing returns clearly sets in later than I imagined. Secondly, you need decent speakers to do the Mini justice. The What Hi-fi review (http://www.whathifi.com/Review/Arcam-Solo-Mini/) recommends partnering with the Dalis, but in my judgement they're not up to the job. Perhaps no £200 speakers are, but I was very disappointed all the same.
Time to get saving 🙂