Hi Wayne; Thanks for answering. What I really need to know is this; does the combo of Pi 3 work with 20 watts of tube push-pull and would it benefit greatly with a subwoofer as the foundation. My point was the Pi4's In my opinion don't require a sub. but are large. The Pi3's are smaller and more realistic for a smaller room and might benefir from a sub. Since I wish to become involved with the new Pi sub. I thought that might make a good combo for a smaller room. The question is does the Pi 3 work well with low power tube amps? I have Altec 421's that make good subs, but I like the idea of an all Pi system.