Martin Logan Clarity Speakers....opinions

enough power not sure about sound though never heard one.

Based on my current ownership of ML speakers, I can only answer one of your questions about leaving or not leaving them plugged in. And the answer is yes, they are designed to be powered up at all times. As for your other questions, please post the specs for the Yamaha to help answering your question .

Hi Rocky,

Your ML Claritys look to want 80 to 200 watts and can dip to 1.1 ohms...  Your Yamaha M70 amp looks like it provides 200 watts @ 8 ohms...  Will your amp work?  Yes...  Is it going to sound good with these speakers is anyones guess...  Is that amp from the 1970s?  If yes then you may want to have someone check that it is still within spec and/or update any parts that may be needing a refresh...
Forward to your two questions:  From my own experience, ML ESL hybrid type speakers like your Claritys sound best with tubes in the mix...  All tubes or a combination of tubes and solid state...  If I'm not mistaken, your M70 is a class A/B solid state amp...
You can leave your speakers plugged in for normal day to day use...  They will go into standby mode when not in use...  If you will be away for several days you could unplug them...
Your Martin Logan Clarity speakers, if in good condition, should sound pretty darn good and bring you many hours of listening pleasure once you get them placed in your listening space as to highlight this ESL hybrid style of speaker.