Isolating different parts (e.g. vocals, guitar.bass, etc.)

Ok many thanks for your replies.

A well produced track, and a good pair of headphones or near field monitors.

I've just bought some etymotic HF3 phones, and frankly the level of detail is astounding even using spotify tracks on my phone. Even though they are a little bass light to my ears, I can follow bass guitars with ease, much more so than my home set up, midrange / vocals equally clear.