I do not have
Sylvania 6SN7W metal base.
But who heard the tube mentioned it is little bit overhyped.
I have Sylvania 6SN7W brown base which sounds lively with good details but not in same class as 1578.
If is better to choose 6sn7 tube based upon what you want to improve.
The advantage of 1578 is nice timber, bass, decay and widest and deepest soundstage.
If you want to go for utmost transparency and details, then you had better get Sylvania vt231.
If you want lush and warm sound, then go for RCA vt231 grey bottle.
Just my 2 cent
Thomas
But who heard the tube mentioned it is little bit overhyped.
I have Sylvania 6SN7W brown base which sounds lively with good details but not in same class as 1578.
If is better to choose 6sn7 tube based upon what you want to improve.
The advantage of 1578 is nice timber, bass, decay and widest and deepest soundstage.
If you want to go for utmost transparency and details, then you had better get Sylvania vt231.
If you want lush and warm sound, then go for RCA vt231 grey bottle.
Just my 2 cent
Thomas