....HD24-Ghost-pre du jour.......the ins and outs on the HD24 are analog. You simply return all your channels to the tape ins on the Ghost. Go direct from any outboard source in to the HD24, set the HD24 to the correct monitoring selection and listen to your track through the appropriate buss on the Ghost. All cables will be TRS as all of the jacks on the Ghost and the HD24 are balanced 1/4". Your outboard pre may be XLR....The Ghost has alarge array of patchable options as far as monitoring any source. I usually listen to tracks through the 'B' buss as i can get a pan and high and low eq to the phones if i need it but the 'A' buss is what i use to mix with.There are also lots of auxes if you need a complicated headphone mix at tracking(ie some jackass wants only himself and just bits of other things). Its your call...........