Can anybody tell me what´s the difference in sound between the Urei 1176 and 1178?(I know, the 1178 is stereo) I think there are only silverface 1178 around. Is there an difference like with the 1176 blackface/silverface? Is there something in serial-numbers that´s important? Is the four- Buttons-In-Trick working with the 1178. Hope somebody can help me.