Yeah for me a scope like the the O'Tool+ or Mordax Data is essential. Yes you should use your ears, but viewing things in the scope can save you a lot of headaches as far as diagnosing problems when things aren't behaving like you expect. I'm a visual person anyway so I like to be able to see things in the scope regardless.
-- adaris
I'm visual too, so I can relate. But also for simpler matters. I have the Zadar, which outputs 0-10V (attenuatable). Suppose I get that down to 0-3V. Now if I invert that, I get -3-0V. Say I want it to be 0-3V. With many DC sources, it's hard to say if I'm really getting 3V. I was using that to AND the inverse of envelope of a sound with gates, in other words to stop gates from triggering while the sound is still playing. By ear, it's probably good enough. Visually, I feel it's more accurate. Now the question is - do I want to spend €500 on a Mordax for that?