Don't get me wrong, I really enjoy my Bottlehead setup. But I can hear the hum between passages. Even without a preamp connected, the Paramours give that hint of hum, and it's pretty noticeable on speakers with greater than about 95dB sensitivity. It's not like an old tube radio or anything, but you can definitely hear it.I have Paramours and a Foreplay, both with C4S and sweet whispers on the Foreplay. The snubber pot is set for the least hum and when the C4S's kick on, it gets quieter but the hum is still noticeable. I use Electro-Harmonix 2A3's, which sound very nice and get rid of the Geiger-counter popping noise of the stock Valve Art tubes.