You surely do not want to use vinyl with such a high latency value. 20 can feel too much (when you’re used to 5), imagine 250…
Given that you use ASIO, and that you have a powerful machine, you should be able to use low latency settings, so we should solve that problem first.
You don’t specify which soundcard model do you use ( the name Echo Audio PCI, is a soundcard from the 90s), but you are interested in a soundcard that has 4 channels in and 4 channels out (at least). (channels as in individual signal, a 5.1 soundcard has 6 channels)
Indeed, first check which sample rate you have configured in ASIO and in Mixxx, since it should be the same. If the soundcard control panel doesn’t specify a sample rate, then it is expected that it uses the one that the application wants, except if it doesn’t support it.
Once you get to play Mixxx without the turntables, then we could start checking what happens to your vinyl setup.
Be aware of these things :
Ideally you would want to use a vinyl preamp (except if the vinyil player happens to have a switch to output in line mode) since it not only amplifies but also changes the frequencies.
The signal boost option is just something that can help, but it is not a complete vinyl preamp by itself.
The kind of vinyl to select in Mixxx depend on the vinyl that you have. Mixxx doesn’t not support all kinds of vinyls so you shouldn’t expect it to work with all models.
It is important that you have a stereo signal, and that you have wired left and right correctly. Mixxx will not work with a mono signal.
The manual contains some instructions when the signal is not correct mixxx.org/manual/2.2/en/chapter … leshooting