Since this thread began 10 years ago (!), I'm seeking some "current state of the art" opinions.
What I want to do is spectrum analysis of my car audio system. I'm not wanting to do SPL. Looking over the the thread and other info, it seems like the Beringer ECM8000 mic is still a good choice, but I need the connection between it and the laptop that I'm going to use for TrueRTA. I look at some of the options on Amazon and I worry about the negative comments regarding sound quality, but I don't know how much these will affect what I'm trying to do.
This gear will be single purpose for me; I'm not looking to use it for anything else, so mixing, additional inputs and the like are not a factor. I'm not wanting to spend over $100 for the gear (assume that the mic, laptop and TrueRTA software are givens, not included in the spend total).
Thanks in advance for any and all advice.