I confess to loving the sound of my 25 year old Naim amplifier. However, at that age and never having been serviced (hangs head in shame) then it is probably not in peak condition. A service has been quoted as £600 for the pair (NAC62 & NAP90, chrome bumper series). There are pre and power Naim items on the second hand market for similar money, and olive series or newer. Any Naim expert care to voice an opinion on where my money is best spent? Do the later series improve the sound or are my cherished old pair going to knock them dead after a service?