I recently put a quartet of TAD RT164 EL34B-STR valves in my Roadster (http://www.tubeampdoctor.com/product_info.php?cPath=21_60_61&products_id=343) and I must say that they've come to stay.
I play in a stoner rock band and wanted to try something different than the standard Marshall approach: a mesa Roadster with 6L6's into a Marshall 1960A cab didn't exactly do the trick! The EL34 switcheroo did however! The amp has a less scoped is more focused in the midrange and tighter in the bottom.
This makes sens to me because:
- I'm playing through a floppy, sloppy, saggy, whatever Marshall cab and this eens up the response a bit.
- It's better for drop C tuning
- the bass player can do his thing: make low frequency noise, without me interfering (!).
Only setback is I started hearing popping noises when changing channels - never happened with the 6L6's.
Spread the word!