Martín Logan choice help

I don't know the Clarity, owned the SL3s 12 years. You should expect to replace the "film" in the stator panel since you are buying used. This may be a significant expense. I'd check with MartinLogan before pulling the trigger. The SL3 is a good speaker but light on bass and needs lots of power to push it. It is fairly "beamy" so the listening sweet spot is very focused. If you are sold on Martin Logan, I strongly recommend buying new.

if you are trying to assemble a new system from scratch, IMO settle on the speakers first then go from there. go to some dealers (if available) to hear what's on offer in your price range. Then pick the amplification to drive them and decide what kind of front end you like.