Tube rolling on Leven CS 600

Good Morning.
I have a Leben CS 600 amplifier driving Devore O93 speakers.  I am using Luna Mauve ICs with a Linn Akurate DS steamer, Feikert Volare TT, and Cal Audio Icon Mark ii CD/Heed Abacus DAC. The Leben came with 6L6GC tubes, but can also run with EL34 tubes.
Overall it sounds great but on some older recordings ( mainly CD or streaming) its a tad bright/forward; in part due to the poor acoustics of my room.
I wonder if some tube rolling might be worth a try.
Has anyone any experience/thoughts?

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?