I agree with the suggestion of Wharfdale 10.1s. That will make the whole thing nice and neutral. Depending on preferences you might want to try Monitor Audios, either BR2s or RS1s, the latter has been replaced, so you may find a bargain, the RRP was £400 but I've seen them for £250, bare in mind these speakers will probably not nullify the brightness of the amp. You could be logical and go for Mordaunt Short to partner CA, in which case the Aviano 1 would be a good bet. I don't know if £300 is the budget for speakers or for 'speaker solutions' which is why I suggested speakers in the £200-250 mark, and make it up to your budget with good stands, Soundstyle Z2s are £60 I believe from Richer Sounds. In addition I'd get hold of some good speaker cable, probably Chord Co. Silver Screen if you got for the MA, or QED Silver Anniversary if you go for the others.
Unless you go for the MA speakers, everything is available at Richer Sounds, Chord Co. cable isn't, but personally I think QED would be a better match for the others, it's a toss up WRT the Wharfdales, but easier to get it all at RS and it might well be discounted.