Tube rolling on Leven CS 600

Hi Pingvin,
I appreciate your advice.  But first a question for you.  Are the GL KT 66   "tall " tubes requiring the lid off approach?
So my system has evolved a bit since the first posting of this thread.  My Linn is now a Rockna Wave Light DAC and a Bricasti streamer.  My IC are Luna Mauve.  My speaker cable is a bit of a problem- as it is in the wall and had to follow RI building code ( thats a bit of a joke )- Tributarie.

I usually ran the CS600 with the lid off, but I recall -- I haven't had it for a few years now -- that the GL KT66 were able to fit below the lid. 
The upstream components don't look to be at fault. I've only heard one system with the Luna cables and it certainly didn't have a harsh sound; based on the company (dealers) they keep, they seem very compatible with the Leben and Devore. That leaves two things: your cables and the room. Can you experiment with, say, some Luna cables and changing speaker position, at least temporarily?
 

I’ve owned Devore speakers since 2008 including the O/93 for 6 months or so. The mids on that speaker were not for me. I tried a couple amps and the A23 before moving on.

It has been mentioned that the coupling capacitors can easily be changed to effect the sound signature as well.  The 1.5uF caps can be changed for something with more body (Jupiters?) or the value may even be bumped up a little for a bit more roundness/fullness though articulation may suffer.  Anyone have experience with this?

Has anyone used the JAN Philips 6L6GWB?

If so can you comment on its tone and midrange?