What I've learned over the past year is how much the room impacts how our systems sound no matter if it is Tubes, S.S. Class D, or Class B (Naim). Further what cables and power cords. I recently redid my audio loft, added newer acoustic panels, and then once up moved them around to learn how they impacted the sound. What I found was a power cord or preamp gain setting what I liked it the past I found in the "new" room was beaten by changing power cords that I might not have liked before but sounded better now, my gain setting on my preamp allows for any input 0-18db of gain, where I did not enjoy the 0 & 6db gain settings I found that now I could enjoy them, where I still lean to the 12db setting, I can enjoy the 6db setting which gives more detail while not as in room as the 12db setting which has stronger bass. My panels are a combination of absorption and diffusion, the panels have a designed front cover made of wood that can easily be taken off. I did that to learn how they impacted sound, I did put them back on due to the room seeming quieter, and more open feeling, but I heard the loss of some weight replaced by detail I wanted a balance of both, knowing what I had up before, I only removed the front defusion panels from the ones on the front wall behind the speakers the M3's Sapphires. Did not take 20 seconds to hear the gain in the body, midbass, and vocals now sounding real with openness but now flesh and bone not just an airy wisp of a voice sans a body, throat, and chest. So with any room, the gear we all choose is what is working for the acoustics of that given room. With just those simple removal of a few of the front panels, I went back and swapped power cords on my gear and line conditioner and wound up with different groups of cords same brand throughout the system that now just make my gear sing without running out and buy new gear to get a sound that I liked in my room with its acoustics which will change if I change what is in that room that I could lose my adding or subtracting from wall acoustics, or furniture, carpeting etc. So is the tube, SS. Is class D or B better? well, I would say any of them could be a winner depending on many factors in your audio room, rooms matter as much as gear. I also will say from what I learned is when we choose speakers it is what works in that given room and its acoustics, which is something we are all dealing with a stuck with and one many don't invest enough in and that includes speaker setup where general setup from manufactures do not mean that is what will work the best in a given room, and its acoustics and size. You have to break rules and try out things so you can learn and train your ear to hear the difference and what each placement does on how a speaker sounds.