I've been using the same audio equipment for a few years now and initially they were exactly what I needed at the time. I posted my set up on how I screencast a few years ago https://blog.driftingruby.com/how-i-screencast/ which gives a pretty thorough insight of the "behind the scenes".
The mixer that I used, the Peavey PV6 USB, had a built-in analog to digital converter which recently started to give out. During a recording at 11PM, I realized that the audio was corrupted. When I'm recording, reliability is an absolute must. I decided to upgrade and remove the mixer from the equation. In order to do so, I needed to get a few different components. I needed a way to equalize the audio, a compressor to reduce peaks, and an amplifier for the microphone. I also needed a new analog to digital converter.
So, to accomplish everything, I upgraded to a PreSonus Studio Channel and a Focusrite Solo. Between the two devices, it fulfilled the requirements.
Earlier in the year, I upgraded the microphone as well from the Shure SM58. It had been a wonderful microphone and there's nothing wrong with it. In fact, I had upgraded from the Blue Yeti to the SM58. However, it is a cheaper microphone and didn't give the quality I was after. So I upgraded from the SM58 to the ElectroVoice RE20 microphone.
The quality of audio on Drifting Ruby is something that I take very serious and want to provide the best possible quality of videos. I know that for most people, it is an afterthought and likely won't even notice the differences. However, to me, a professional quality audio is important and something that I feel that I've accomplished.
While there is much better equipment available, I feel that it would be diminishing returns. Higher grade equipment would likely not only be overkill, but it would also not make a noticeable difference. After all, I am just working with a single channel.
While I'm still optimizing the new equipment, I hope that you enjoy the content!