To me i think tube pre-amps gives you the best of both worlds. you can roll the tubes to find a better sound to you. then you still can have a powerful compact speaker amp or headphone amp. i want to get one but it seems like every time i get the money something else happens, LOL
tubes will have a red-ish glow to them, since these are pre-amp tubes. they will not get a red or glow brighter as amp tubes do. this is in part due to the amount of power/voltage running through them. any color from the bottom like that at the tubes will be leds. tubes will not be that deep red color, they will have a more orangish glow like dimmed incandescent light bulbs.
interesting, looks like some tubes do have blue in them. it looks more like the edges of where flow starts for the electricity.