My favorite is the 7316 sub for a 12AU7. I use them in my Jadis DA 60 but have rolled them into several different integrated amps with great outcomes. They are very good for upper end detail and have a soundstage that is unreal, in a good way. They are scarce and to my knowledge were only made around 1960 and only by Amperex Holland. The one caveat is that they can be very expensive these days. OTOH what good tube isn't? If you like the clarity of the Siemens for a strong clean signal try that other German tube Telefunken ECC82.
BTW as my old friend says quoting Kondo San nothing is unimportant. The 6SN7s do have an impact on the sound the Sylvania GTB IMHO are very nice somewhat warm tubes with a euphonic midrange. I won't write a novel about the available 6SN7s to try. They remain the only tube that is infinitely better as NOS or OS than anything new. Please note that I emphasize infinitely better. My own tube collection contains mainly older tubes. However new production has begun to climb up the lader as true NOS go extinct and pulls or throw away tubes are what appears to be what is being sold.
BTW as my old friend says quoting Kondo San nothing is unimportant. The 6SN7s do have an impact on the sound the Sylvania GTB IMHO are very nice somewhat warm tubes with a euphonic midrange. I won't write a novel about the available 6SN7s to try. They remain the only tube that is infinitely better as NOS or OS than anything new. Please note that I emphasize infinitely better. My own tube collection contains mainly older tubes. However new production has begun to climb up the lader as true NOS go extinct and pulls or throw away tubes are what appears to be what is being sold.