This ad is for a very slightly used balanced AKG K7XX in excellent condition. The balanced mod I got for this AKG K7XX cost $120 on top of the price of the headphone. They put silver wiring inside of the headphone, and the balanced cable is OFC copper with Neutrik gold connectors. Total cost to me was $320; selling here for $230. Has a more transparent and lively sound than an un-modded K7XX. For an extra $15 I can also include a balanced to single ended adaptor if you want to use these with a single ended amp as well as a balanced amp at any point down the road. For $25 extra I can also include a 4-pin XLR balanced to 6.3mm TRS single ended adaptor so these can be used on single ended (unbalanced) amps. Thanks for looking!