@dmac67 if you search I was able to find internet radio stations that play white noise last time I looked.
31hz isn’t perfect but still very useful. Many hifis sans sub start to roll off well before that especially in larger rooms. The key is to keep the room response at your listening spot as extended and flat as possible. That enables every inkling of bass to be heard at proper levels
I’ll give Baba a play and report back.