(Those more knowledgeable, please correct me if my memory is faulty on this.) If you're looking for "ruthlessly revealing" monitors for recording/mastering, the LS 3/5a may not be ideal. While intended for use as monitors, they were designed by the BBC (IIRC) for mobile-recording situations, i.e., mobile vans, etc. They were also (again IIRC) designed for monitoring the human voice. They are famous for a mid-bass bump to give the illusion of deeper bass. Thus, they are not the flattest of monitors. None of this prevented them from being enormously popular and beloved in the audiophile community. Sorry I can't give you any advice on amplification.
-Bob
-Bob