Hi Halifax,
I haven't had this BAT VK-5 very long, but Oh my what a difference there is between this Pre-Amp and my SFL-1. I have even had my SFL-1 Modded with larger and better caps. I know that I can make very slight changes by tube rolling with the SFL-1. Nothing like the changes I can make now with the BAT VK-5. And the 8 (6922) tubes it takes. Please don't get me wrong I have enjoyed my SFL-1. But it's not even on the same level as the BAT VK-5. I can't believe the difference. I can't believe how much music I was missing. Also how the music is so non fatiguing even after 6 or 8 hours of listening. the best way I can explain it is that you feel the music it seems to come to life. I hope that helps you