I find great 'synergy' between my Rega R3's and the Solo-Mini.
When I bought the Arcam and my speakers, I auditioned the Monitor Audio BR2's (a WHF recommended pairing at the time) and some entry level Focal JM floor standers. However the Rega R3's were an absolute stand-out! (They were £500 apeakers on offer ex-dem for £399, so about twice the price of the BR2's to be fair.)
The R3's are quite efficient at 89db and I don't enjoy ear splitting volumes so the Solo-Mini's 25 watts per-channel is ample for me.
Whatever you do choose, try to get efficient speakers (around 90db or better). Your budget appears (from the price of the KEFs you mentioned) to be about £400 so try to hear the new Rega RS1's (£398). They are plenty efficient enough (90db) and have the new custom designed Rega tweeter which - by all accounts that I have read so far - is epic.
Monitor Audio's ranges (Bronze, Silver) are pretty efficient too but I am only familiar with the BR1's and BR2's. The MA RS1 (a WHF 5 star reviewed model) could be just the ticket and around £400.