Line regenerators (PS Audio, Accuphase) can be likened to amps, I suppose. I've run solid state amps on occasion vertically on the side, but not directly on the floor, but with something to stand them on, in order not to impede the flow of ventilation around the heatsinks. Never had any trouble. Would not want to try it with tubes. Have not done it with my PS Audio 300 and 600, but here I would not have any qualms about it, if I had to.