I would avoid using jumpers or having connections of different lengths if possible. If I were in this situation, I would find ways to locate the amp one foot closer -- proper location of speakers is usually much more critical than amp location. Of course, you must already have considered this and rejected it. If so, I recommend replacing the speaker cables with the proper length, which is the textbook solution. Perhaps you can sell the too short cables on Audiogon and buy a longer pair cheaply here, too. Good luck.