[quote user="silly"]I would look at prima luna, Copland, Puresound, unison research, sudgen amp wise if I was you, if your going to upgrade , then make the upgrade worthwhile, also then look at speakers from Sonus Faber, pro-ac, diaphson, opera if I was you, it will suit jazz music rather nicely indeedly.[/quote]
Silly, check the guy's gear out - he's playing out on the first rung of the hifi ladder (no disrespect mate); slapping in a £1200 Sugden, Copland or any of the others only adds a complete imbalance and shows up what the system isn't capable of.
Over and above the Marantz and Rotel, you could seek out the earlier Marantz PM7200 which will be a good upgrade from the Cambridge, has a Class A performance belying the outlay and will itself withstand upgrade. There's Audiolab's recent 8000 back on the market again too to name but two.
All depends on your budget, but anything up to the £500 bracket will serve you well just now and for an upgrad or two yet. Spending more is probably unwise unless you want to boost elsewhere (and to a similar standard) too,