The electrons are free of molecular collisions in the hot glass compared to all that doped silicon so more signal gets through. You could say that the vacuum gives you more air.
Tube Amp soundstage
I hope everyone is safe and healthy during these strange times. I wondering if someone could explain to me the reason my tube amp has a deeper soundstage than my SS amps? Two years back I built an Elekit 8200 which puts out around 8-10w/c in ultra linear mode, depending on the power tubes. I usually run KT88’s or 6L6’s, and less often EL34’s. It powers a pair of Tekton Enzo 2.7’s which are quite efficient at a claimed 98db. The SS amps I’ve used with these speakers include a vintage NAD 35w receiver, a Musical Fidelity m3si @ 85w, a Rogue Sphinx @ 100w and a Hegel H80. Now granted, non of these amps are what I would consider high end audio, but no matter what, the little tube amp always seems to have a deeper, more 3-D soundstage and the SS amps sound a little flatter. Same source, same DAC, same speakers and cables. There are things I appreciate about the SS sound, such as tighter, better defined bass and an effortless ability to play louder (which I do less and less), but every time I rotate the little tube amp back in, I hear a slightly more organic sound and that deeper soundstage.