Hi Outlier; I have faced this question with a SF Line 2. I like the stock 6922 Sovteks pretty well, but the Valvos (from SF) are smoother, sweeter, a bit warmer and more tube-like. I tried an exotic set of tubes from Upscale Audio in LA: Amperex 7308s in the forward positions, but got a really un-natural, big, bloomy, soundstage that I didn't like. Still, I'd recommend Kevin Deal at Upscale as an expert on SF tube equipment. He's at www.upscaleaudio.com Just explain to him what kind of sound you want. Good Luck. Craig.
4 responses Add your response