My Stingray had the warm sounding Ei 6BQ5/EL-84 tubes...I was very happy with them. Some folks like the Mullard which are also warmer sounding..but VERY expensive. An octet of them will run you near $2K. The other nice tube is the Tungsram old production. I felt that the Ei offerd a lot of sweetness and slam for the paltry price in comparison.
As for the 6414 driver tubes..Not much to be gained by switching those out. For inputs...I used an old GE 6201 that I liked much better than the newer GE 12AT7 JAN tube..TFK are another nice tube. Check out Andy's website at Vintagetube.com to get a look at some of those. His Superline Mullard/RCA/Amperex or TFK are some of the best sounding.
As for the 6414 driver tubes..Not much to be gained by switching those out. For inputs...I used an old GE 6201 that I liked much better than the newer GE 12AT7 JAN tube..TFK are another nice tube. Check out Andy's website at Vintagetube.com to get a look at some of those. His Superline Mullard/RCA/Amperex or TFK are some of the best sounding.