I've been practicing with some kind of recorder consistently for the last 10 years. For better or worse, I believe that every student must learn proper self evaluation. During my student years, I've gone from the low tech mirror, to the high tech webcam mounted on my bridge, and Zoom handy recorders. I've used my trusty Dr. Beat DB 90 as a drone tuner, and Pano Tuner app as a visual guide. I've used electronic keyboards and music notation software (Finale and Sibelius) as pitch matching guides. I've embraced technology to its fullest as a professional cellist and educator.
All of my students have access to a video recording device on their phones, or their parents' phones, so there is no excuse not to start the self evaluation process immediately. Besides technique, I teach my students self evaluation using mirrors (low tech) and audio/video recorders (high tech).
My current practice setup is in the above picture. I use a Zoom H5 recorder in live monitoring mode with the mics 1-2 inches from the bridge. The gain is set to where I can comfortably hear every single scratch and inconsistency in sound. I listen through the Westone UM50 in-ear monitors (IEM's); I've used Shure and other Westone IEM's before. For the reference pitch I use Sibelius Ultimate; I've used Finale and other versions of Sibelius before. My laptop is connected to the Zoom via one of the inputs, which mixes with my tone in the headphones when I play along. Sibelius is furnished with Note Performer 3.2, usually on a non vibrato setting of an organ, clarinet, or solo double bass. Of course, some knowledge of notation software is required. When using an electronic keyboard, you can use the same setup, only you will need to record the excerpts of music you are practicing, and you won't have as many saving options.
I hope that this post will be helpful to people who are looking for new practice techniques. This technique is definitely not for everyone. But if you are an auditory learner, this technique could be a lifesaver and time saver.