Rectifier Tube Rolling in a Modwight LS 36.5DM

@robergerman
" If you desire a "different" sound you can try different makes of the other tubes in your preamp: 12A*7/ECC81,82, 83's/5751's, 7025's, 6DJ8/6922/ECC88's, 6SL/6SN7's ..  This is a SAFE method!"
Not sure what you are telling him as his preamp doesn't take these other tubes.
" Tube brands DO NOT have distinctive tonal qualities"

So, all tube brands sound alike? Not sure what you have been listening to.

goffy
I use a NOS Philips 5AR4 rectifier in my Modwright LS100 preamp , and a NOS Mullard 5AR4 rectifier in my Modwright Elysee DAC , haven't had any sound "anomalies" using either; and found both to be better than the stock new production rectifiers

@robergerman
"I don't know the tube complement the LS36.5 DM uses. Just thought I'd list the most common preamp tube types! "
He listed it in his opening -  6H30 DR . 

roberjerman -  tubeworld contradicts your finding that the 6H30 DR and 6CG7/6FQ7 are equivalents
" a 6FQ7/6CG7 is electrically similar to a 6SN7GT, but a 6FQ7/6CG7 has 9 pins versus 8 for a 6SN7GT "
and from fourwater
" To address this problem, the 6CG7 was created which simply put the 6SN7 elements into a 9 pin minature tube. The main difference is that the plates of the two sections are slightly closer together because of the narrow confines of miniature tube. They did add a twist though, since there were 9 pins available, they decided to add a shield between the two triode sections and bring it out on the extra pin. This was used to keep the two sections isolated, which can be especially useful for high frequency use. This made the tube slightly more expensive to make, so later the 6FQ7 was created which eliminated the internal shield. "

Haven't been able to find any online source that states that the 6CG7 is a drop in replacement for 6H30 ; what did Roger have to say?