You will generally find the unit to sound less harsh with NOS tubes. Audio Research distributes Sovtek tubes.
Personal preference and system synergy will have big impact on your choice of tubes. Check JoeS's excellent comparison on many 6DJ8/6922/7308 variety tubes on AudioAsylum. His description of tube sounds provides an excellent reference. People have recommended Tungsrums and Russian 6H23s. I currently have 3 Amperex 7308 white labels in my unit!
FrankC
Personal preference and system synergy will have big impact on your choice of tubes. Check JoeS's excellent comparison on many 6DJ8/6922/7308 variety tubes on AudioAsylum. His description of tube sounds provides an excellent reference. People have recommended Tungsrums and Russian 6H23s. I currently have 3 Amperex 7308 white labels in my unit!
FrankC