How do you check if an audio amp is receiving and/or sending audio?

[benime]

Here's what I get just testing with DDP DOJ.

Those are some hot jams! @benime. Not to derail the thread, but seeing it in the video made me remember that I need to put a new fan on my DDP DOJ Case. Do you know the replacement specs by chance?
On the topic of the thread, I needed a logic probe so this thread also got me to pull the trigger. Thanks for the example video.

I replied in your thread, too, but 60x60x15mm.