pair NOS GE 6GH8A w/ Adapter to 7199 PREAMPLIFIER VACUUM TUBE.
This is one opinion I read about the 6GH8A tubes
- Imaging between these and the 7199's were about the same but the sound stage improved 10 fold. They have a much better, open and detailed upper end with an excellent, fluid mid range. The depth of the sound improved 10 fold as well. These 6gh8a's made a night and day difference in this amp.