Ear training course intervals questions

Even an inexpensive department store keyboard will be quartz accurate these days. Don't have to spend a fortune on one and an app would certainly work just as well.

I'm old enough to have grown up when pianos were virtually all made out of wood and didn't run on electricity, so I like having a decent weighted action yamaha digital piano in the house. I use it a lot, though I'm not at all proficient at playing piano. Something about having the keys all out in front of me helps establish the logic of music and over the years, I've developed rudimentary sense of where a note would generally be on a piano upon hearing it.
well said, this is why I don't want to use an app or other virtual keyboard. With an onscreen "keyboard," there is too much of a disconnect for the relationships to fully gel. At least for me.

Similar to how handwritten note-taking is superior to typing notes into a laptop.

At the same time, it doesn't need to have all 88 keys, be velocity-sensitive or of concert-quality fidelity.