If you have the budget, then Rega RS1's (£390) will be excellent partners. Very efficient at 90db (8 ohms) and a lovely sound.
They are also available in Piano gloss black (or white) for a 10% premium. (Or standard real cherry veneer.)
Gloss black will be the RX1

But I agree, the RS1 would be a great partner for the Solo, especially at their clerance price.
Inter 84 - the Arcam may not look like it produces much power on paper, but it's far more powerful than any other 'mini system' at a similar rated power. We've used ours with the 684 and 685's, ATC SCM7's, ProAc Tablette 8's, and the RS1's. For normal volumes it has more than enough power for any of these speakers, and you'll only find it struggling if you like listening to Prodigy at club levels or you're playing it in a larger than average room.
David
Frank Harvey Hi-Fi Ltd - now on Facebook (search Frank Harvey Hi-Fi)