Upgrade Advice needed for 2nd system

[saaliqeh]

The missus has n't caught on yet but i'm getting that upgrade bug again .
Having bought a Marantz SR7500 Receiver 9 months ago i'm now thinking about finally upgrading the stereo set-up in 'my' study (my one haven from the wife and 2 kids in the house!!). The current set-up there is a mixture of hi-fi that has been relegated from the main system and is as follows:
Marantz CD60SE
Rotel 840bX amp (must be about 15 yrs old now !!)
B&W 601 s2 speakers

The room is only 3.4 x 2.3m in size and my music tastes are largely rock/pop/ AOR and a little classical.
My budget is £200-350 to upgrade the amp and I have seen the following second-hand integrated amplifiers:
Arcam A75 £200
Arcam FMJ A22 £300
Arcam A85 £350
Marantz PM7200 £275

Any advice on the best value for money amongst the above amp's or suggestions for alternatives would be gratefully received.

Nb. At a later date (ie. finances permitting) I was looking to get either a Marantz CD17 or an ARCAM cd player.