Eric, not sure what you mean by adapter (and please don't be insulted if you already know everything I'm about to say--just trying to help). You must use Ubisoft's proprietary $30 cable to plug your guitar into your Xbox, PS3, or PC. Thankfully, the same cable works across all three platforms. The rule of thumb is that if it's a working guitar that can be plugged into an amp and produce sound, it'll work with Rocksmith. However, some guitars produce more undesirable distortion within the game than others. Looks like this thread was created to help identify how well various guitars performed.
Works good with my Les Paul Goldtop but the lead pickup is not very loud. Not sure why as this should be the hotter pickup. I am going to try it with my other guitars including a single coil strat to see how well that works.