I just recently tried some el34 SED ( not Svetlana ) cryo quads and the difference is deffinetly there. At least for my system . If I was to put a percentage maybe 10% better. The difference I found was refinement all notes were crisper and had better definition ( not brighter ) in the highs, with the mids bieng a touch more organic ( a touch more meat on the bone ). And the lows didn't seem any difference whatsoever ( that I noticed ).
I will however by more of the same ,so its enough for me to re-buy and sheck out the extra cost.. This is only one situation and one tube type! I can't vouch for any others However, I just placed an order for 2 other pairs.1 Pair 12bh7a GE cryo'd and 1 pair of EI 12ax7 cryo tubes.I hope they work as well as the others...Not sure if that helps or not....
I will however by more of the same ,so its enough for me to re-buy and sheck out the extra cost.. This is only one situation and one tube type! I can't vouch for any others However, I just placed an order for 2 other pairs.1 Pair 12bh7a GE cryo'd and 1 pair of EI 12ax7 cryo tubes.I hope they work as well as the others...Not sure if that helps or not....