Audio Research Pre Amp LS15

LS-15 doesn't have a built-in phono section. You'll have to get a separate phono preamp to use with your TT and the connect the phono pre to any available LS-15 line-level input.
As far as i-pod, I think you can connect it if you use mini-plug-to-RCA cable.
I am no expert in i-pods but I this Audioquest makes this cable that will allow your i-pod to be used the way you want http://www.amusicdirect.com/products/detail.asp?sku=AAQMINI3%2D1M

iPod has a mini jack on it that allows a stereo connection to a preamp. Simply choose a line-in source as you would any other component. I run my MacMini iTunes into my rig like this, and it sounds great (plus I can EQ the signal on crappy recordings). You'd have to look for a phono input for a TT.

Thanks for your help guys. At least I know I can play my Ipod in my system.

Daniel