If you are looking for a preamp to improve and shape your signal you will most definitely love the WA12-500 MKII. The WA12-500 MKII is designed to transform plain instruments and vocals into exciting tone. If your mixes lack depth, struggle to sound alive, or are just missing that professional touch youve always wanted, there is a good chance you will love the WA12-500 MKII.The WA12-500 MKII is based around a discrete op-amp, the X731, which is our own reproduction of the vintage classic Melcor 1731, considered by some to be the warmer predecessor to the modern 2520-style op-amp. The X731 can achieve vibrant, clean and lifelike tones; but can also be driven into mild saturation at much higher gain levels. The effects can be subtle, but very pleasing to the ear. The WA12-500 MKII can also accept any discrete op-amp on the market that conforms to the +/-16v, 2520 pinout standard.