I have two JCM2555's, (one for sale on here by the way)and a 2554 Silver Jube combo and agree that they are probably the best sounding amps Marshall have made.
Re. the comment about not coming up for sale often- I kind of agree, but the non jubilee 2555's (ie black and not silver, made after 1987) come up even less. I've only ever seen three in the last 8 or 9 years and I bought two of them!!!!