The performance, and sonics, of both tubes, will depend on the circuit, they are used in. To me, the Svetlana's, sound better, when the circuit is biased, on the high side. The Electro Harmonix, does not seem to like this. As with all tubes, the end sonics, will be influenced by the circuit, bias, and amount of current, that passes through the tube. In one amp, they may be heaven, and hell, in another.
