When we get stressed, we tend to get more symptomatic. When I was first on antipsychotics the hallucinations stopped completely, for six to eight months. Now that things have got increasingly stressful I have the odd breakthrough symptom... but it's not too bad, since I know a, what's causing it, and b, what symptoms to look out for.

If you are aware that the voices hallucinations, whatever, aren't real, you're already most of the way there. It could be an early warning sign that you need to do something to reduce stress in your life. But to answer the original question... yes. From my point of view at least it's perfectly possible to have audio hallucinations (even visual ones) and to be perfectly fine and happy.