I am starting a new thread to further a discussion begun on page three of the following thread: (Dead Link Removed) I did research on voltage, current and Ohms Law (which was not passed by an act of congress, suprise) this morning and think I have a better grasp of these ideas. I also came upon this article http://www.rane.com/note110.html which I found helpful in understanding the use of balanced cables. So now I have a few questions. When hooking up a guitar to my Presonus unit using the obviously unbalanced cable from a guitar, the manual states that the first two channels are instrument ready. The use of a DI box then is not really necessary is it? Is an isolating transformer as mentioned in the above article the same thing as a passive DI? Or is it another creature altogether? Should a DI for guitars or bass be active, as my understanding (or lack thereof) of some of Remy's posts are that passive units are not correctly matched in impedance for transmisitting the impedance levels of guitar pickups?