I needed new same constructed drivers for the SA3000, which originals were replaced in a defective SA5000. Drivers transplanted into SA3000 with added 10 Ohm ground resistor to up the impedance to 34 Ohms. Now the SQ is Hi-Fi without using extra headamp, All portable music sounds amazing without fatigue! like the SA1000. I'm happy with SQ. Only a dampening modding the ZX700 will probably fix the wrong unbalanced lifeless brassy SQ! --- Greatest Sony design bug ever and they use same design over over again!? z1000, zx500, 7510 , 7520 etc. They must...