Sorry I forgot to add, I would be very cautious about buying a 120 V amp with an IEC lead, because sooner or later someone will plug a UK IEC lead into it and plug it into 240 V.
With luck you will only blow a fuse, but you could also be looking at a new mains transformer + other components in the power supply that "don't like it up 'em" eg filter caps.
Sadly, I've seen this happen too many times........