6N8 tubes

I have a new amplifier (Dared MP-60) equipped with 6N8 tubes as drivers. The amp is very good (I have already replaced the stock Ruby 12AX7 tubes with Sylvania 12AX7A/7025 which added high frequency crispness, air and focus. Are 6N8 tubes any good or they can be improved by Sylvania, KenRad VT-231 or Brimar black glass 6SN7GT?
6N8 is a Noval base(9 pin). 6SN7 is Octal base(8 pin).

They are not at all similar in pinout. The 6 as first digit means 6.3V heater, thats the only similarity.

The 6AD8, and 6DC8 will substitute for 6N8.

John C.
The Russian 'N' looks like an 'H' and so the Russian 6SN7s are often marked '6H8' when the actual number is really '6N8'. You may run across Chinese 6SN7s that have the 6N8 number on them.

If this seems confusing its OK- it is :)

So if this is what you are dealing with, then the answer to your question is 'yes'. I would of course check with the manufacturer to make sure there are no voltage rating issues that might require a -GTA or -GTB-suffixed tube.