G,day Gil.
Like Barnacle said no probs in coin relic mode.
In prospecting though I think silent searching would see you not getting the best out of your machine. I listen to those faint changes and slight rolling threshold changes a my "key" to make changes to various settings and my sweep speeds and so on. You can learn a lot in prospecting mode when hunting for gold by listening to those background threshold sounds. With no sound though it will take big changes before you become alerted and by then you could have walked over meters and meters of good ground without knowing you should be doing something different.
I owned a Tesoro Eldorado which silent searched and for coins and relics I had no probs using it in silent but for gold nuggets no way.
And then again we all are different and I have mates who never use a threshold for gold nugget hunting, but, I can follow them where they have been and find gold they never knew existed too.
Good luck whatever you hunt.