IS THE MARTIN LOGAN Renassance 15A worth the $10,000 higher cost than the Expression 13A

i have the 13a's .. love them...15a 's provide more of the same sound...the signature sound holds true from the 11a to 15a imho.

my room is 17 by 16 and they work nicely... 

these speakers are very revealing.. they will demand good clean electronics and wires upstream for sure.

i like to use solid state amps with tubed preamp.. i use krell/arc combo with mit wires

https://www.audiogon.com/listings/lis97d8i-martin-logan-esl-15a-gloss-black-nib-never-used-full-rang...

I am also tempted to get one as my second system.

Second the idea that you need the best electronics you can get with Martin Logans. They are very transparent and you will hear any money spent or not spent upstream.  They like power too.

I have a pair of 13A they are very good speakers, you can not compare them to box speakers the clarity the expanse is very good. You do need good power to run them and the better your system the better sound.  But this is true for any good pair of speakers, so don't get scared by comments above.Go listen to them.