AC Powerpacks

Hi.
I've almost finished building a preamp based on some of Rod Elliot's designs. I'm using the P05 powersupply, and have just bought a 16VAC power-pack.
I just wanted to know if it's OK for the 0V live of one of these powerpacks to touch the main chassis? The pack is double insulated, and it does have a main earth connector, but all the sockets I've seen for these (2.5mm) are not insulated.

Thanks.

(I posted this on solid state, but I think this forum is moer appropriate :) )