I'm going to throw the cat among the pigeons here. I've heard LS3/5a a few times and remain extremely underwhelmed. Sorry to those that love them, but to my ears they are dull, flat and undynamic. In a word; boring. If I had £1000 and a pair of free LS3/5a than I'd sell the speakers and buy a decent amp/speaker combination for a lot less money.
If they are loaners, they why bother? If it's short term and you've got a grand to throw around, there are many alternative combinations that would work far better.