Well there can be problems caused by the fact you then have two crossover systems on the same circuit, and each speaker likely has more than one driver in the box...It is not like series connecting raw drivers INTO a balanced system, and some crossover components bridge the positive and negative lines, resistors are sometimes used for this,to adjust particular driver volumes, so forth. It could cause problems, and won't sound any better. Suffice it to say doing it will not reap any benefit. You should use a high current amp with such low impedance speakers, Certainly you will not want to crank your 8 ohm spec amp when they are attached normally to the 4 ohm speakers, and will want to monitor the amps internal heat, and keep it WELL ventilated. -Perhaps even uncased. .