I know the perfect solution. Have you ever heard of silicone, that's polymerised silicon, the stuff fake tits are made from. Silicone is one of the most versatile resistant materials available today. It comes in a variety of forms. It is considered something of a super material. It comes in gels of various viscosity and stickiness etc, it comes in hard and soft rubber and plastic forms. The list is endless. I would suggest using a gel and casting you components in it, a bit like potting systems into boxes. Instead of using potting compound, use a silicone gel.
I have used something called SILGEL 612 before, it is one of a very wide range of silicone products made by Wacker. This one is probably a little too unviscous for your application but it's a good start. It has a very high thermal conductivity and dielectric strength. It is sticky and soft, yet extremely resistant to plastic deformation. Here are the two best properties, it is probably the best, if not one of the best materials ever for mechanical isolation (especially audio frequencies), this means that you will not even hear a peep, and it comes in two parts, you just mix them and pour into your potting container (with your components of course, making sure your board is not touching the side and the noisy one has the most material around it) and it will vulcanise within 8 hours at room temp (I think). It's not that expensive, and if you play your cards right you might be able to get a free sample, Wacker usually send out 1L samples, PM me if you want to know telephone numbers and distributors.
Hope this helps