Hi I did a search and found a few sparse opinions on these new production, Russian, Tung Sol 6550s. What do people think who have used them for SVTs? The original 6550s by Tung Sol were absolute tanks. A good friend uses them in his Leslies and they get tossed around by roadies and he has never had a problem. I have some random ones lying around but not a complete set. How do people think they compare to the EHX or Sovteks or JJs? Do they have any of that original NOS magic? They are offered at a pretty attractive prices here in the UK. thanks in advance.