Tip via AI:
Pomp and Pipes! (Reference Recordings RR-59CD): Known for sun-20 Hz signals,especially tracks 4 and 9.
Here is track 4:
As usual when I listen to classical music, with much quieter and explosive, dynamic parts, I need a lot of power. Now with a 120-watt power amp, and that's why I'm testing bass now, with a pair of used super bargains (a scratch on one of them), Audio Pro Black Diamond v1. I couldn't help but buy them. Sandwiched in the corner of my listening room, with downfiring bass. Bass is down 28 Hz according according to spec. Hum. I'll measure it later.91 dB sensitivity, maybe, but I find them to be fairly sensitive anyway.
View attachment 516135
Now testing the music track above. Speakers without a sub. Pretty good I must say.

Here are pictures of them before I popped them into the corners the in my room:
View attachment 516132View attachment 516133View attachment 516134
Edit:
Even though they are now measured in my room, with WiiM RoomFit and UMIK-1, it may give some indication, around 33-35 Hz f3 from what I can see. It was surprisingly good, I must say.