Late as usual to another thread, on my TD backpack I basically took a old 2" PC speaker spliced in a 3.5mm cable with a male jack. Picked up a $20 audio amp at Radio Shack, plugged in the speaker cable out, installed a 36" 3.5mm patch cable into the inlet side of the amp, the other end into a $10 mp3 player i connect to my canvas belt.
On my TD the radio face has holes simulating authentic radio speaker cover and finished drilling through the cover and glued the speaker in place just behind that area.
Our HWT packs are quite a bit different especially they're not a s detailed (IMO).
Has anyone tryed something similar with the HWT packs and have any pics?