Most definitely! I think if you are just getting into tubes, my favorite intro is the (Mass)Drop.com Eddie Current ZDT Jr. Or if up to it building a Bottlehead Crack.
But, if tubes are next I would keep the 6xx as they would benefit the most from tubes … I wouldn’t pair planars or the Focals with tube amps unless they can bring down the power output (I’m not the best qualified to talk on this, but planars and Focals tend to get blown out/bloomy sounding on tube amps… especially OTL tube amps).
You might also look at a tube hybrid like the Schiit Lyr, Drop.com MCTH or even the Loxjie
sorry for not linking the threads to the other amps…I’m on my phone and it’s a PITA lol hit the search icon on the top and search the forums for them 