tubes for Kora Galaxy Reference

In this amp, I have Sovtek tubes throughout, and was hoping that someone could advise on which tubes (current production or NOS) work well. Would Svetlana be considered a worthwhile upgrade over Sovtek for the 6AS7G? Between the 6922 and the EL84M, which one is more critical to the sound and would thus provide the greatest benefit of rolling? Is it critical to use "EL84M", or can regular "EL84" be used as well?

In my system, the amp has good clarity and detail, but is a bit dry and lean, and lacking in musicality. Looking for a fuller more enveloping sound w a bit more "flesh on the bones", and better involvement and emotional "pull". Speakers are Coincident Super Eclipse; cdp is Metronome CD2V Signature; Manley Control Master preamp; all Coincident cabling.

Thanks for the help.
Get rid of the Sovteks! Buy the best 6922s you can afford, they are the most precious of the bunch and may affect your sound the most. Contact me about 6as7 and el84 if you want to play with inexpensive old stock.
The Sovtek and Svetlana of that tube were both made in the the same factory. You will not notice a difference.
You should use the EL84M but some other EL84's will work as it is a heavy duty version of that tube and they recommend it. The Phillips SQ is a very good tube for this and will make things more musical over the standard Sovtek.
I recommend changing the 6922 tubes to Siemens or Telefunken.
You will need to rebias the amp after changing any of the tubes. The El84's should be biased first at 20 volts. If you are going to change the 6922 make sure you put them in before you bias the EL84's. The Power tubes should be biased at 700 mv. Higher bias will make it softer (classic tube sound) lower than 700 will give you more dynamics and punch.