That's a bit of a tough call for £400 or less.
The 15 ohm load should present no problems to any modern amp. The speakers are quite revealing of amplifier character and of the names you mention, I'd suggest looking at Creek amplifiers. They sound clean, without harshness. You probably should be aiming at around 50 watts as a minimum power output, not so much that the LS3/5a has huge power handling, it doesn't, but it responds well to the grip of decently powered amplification.
It is impossible for anything digital to sound analogue, because it isn't analogue!