People normally aren't too grouchy about ressurecting threads.
I just went in an isolation tank for the first time two days ago. I went in half-expecting to trip out with visuals and an OBE. It didn't happen and I was kind of bored, waiting for something to happen. I realised my expectations were marring any potential experience, but I've never been too good at meditation so that didn't help.
Anyway, it was relaxing and my breathing gradually slowed and became automatic. About forty to fifty minutes in, I fell asleep... or something... but it was a very dark and deep sleep, or I just didn't remember what I dreamt about. Basically my mind became very relaxed and all my thoughts 'unwound' in a scrambled, chaotic, yet somehow alleviating way. My consciousness dimmed almost to the point of nothing. I've experienced this at least once before, using holotropic breathwork (only tried it once).
Then the music started playing, my cue to leave the tank, and I came back to consciousness in panic. I was taking deep but frantic breaths to calm myself down. Paradoxically, my body was so relaxed that the breaths came very easily, and soothed me at once. It took a few moments for the panic to subside and for me to realise I was in an isolation tank. I got out quickly, as I suddenly felt claustrophobic.
I spent the next three hours wandering the shopping centre in a quiet brooding mood. I thought about my life, the deprivation tank and my recent plane crash of a mushroom trip. I felt calm, but weird, like I was vaguely tripping. It was a process of absorption and reflection and I feel it was quite healthy, if melancholy.
Your mileages may vary; I have a lot of unresolved issues bubbling below the surface and the isolation tank, like the mushroom trip, brought them to the forefront of my consciousness. The isolation tank, however, did it in a way that was far more manageable.
I have booked in five more sessions. I plan to use one of them under the light influence of something, perhaps 2c-b (my latest craze) at about 10mg, to stimulate psychadelic or maybe hypnogogic consciousness. Don't see anything wrong with doing that but I would definitely recommend doing it sober the first time.
And if they ask whether you'd like music, no, you don't. That defeats the purpose of sensory deprivation.