I am starting to get into electronics and also seeking some powerful speakers (used probably). I've read some posts about generating frequencies/measuring the same, but what are other ways to test speakers, locate electronic or acoustic flaws, etc, (beyond visual inspections)? I will procure an oscilloscope, I have various electrical meters, and tone generation is easy enough, but what else could I use, if anything? I realize that this is a fairly broad question, but any other input, whether it is general or specific, might help me to realize something I am missing at present. And if you have any test equipment that you are looking to sell, please send me your contact information or a link. Thank you for your input.