MARSHALL IGRO, А и B
There were two versions of this amp. Start of production until about September 1993 Mark IV's are referred to as version A; amplifiers made from late 1993 until the end of production in 2008 are known as version B. Early B's have an attached power cord, like the A version. Some differences: version A has no footswitch for reverb or stereo effects loop, and the lead channel is much like the Mark IIC+'s. Version B has switchable reverb, a single switchable stereo effects loop, and an output to drive another power amp. Its voicings are altered slightly.