The NAC 552 preamplifier had an almost impossible task when it arrived in 2002 – replacing the legendary NAC 52. In fact, that task fell to the NAC 252: the NAC 552 took the concept of that superb preamp, by now 12 years old, and built on it to create the very best preamplifier Naim was able to develop at the time. 18 years on from its launch, and with only an upgrade of its offboard power supply in 2012 to DR specification, it still remains one of the world’s great preamplifiers, and bettered only by the NAC S1, which is part of Naim’s Statement system.
As with the NAP 500, the NAC 552 comes complete with a dedicated power supply, the 552 PS in a separate enclosure, isolating the preamp from any interference effects of the mains transformer. The split-rail power supply uses a sizeable transformer, along with three smoothing capacitors and DR technology, with two cables connecting the power supply unit and the preamp ‘head-unit’, multiple regulated feeds delivering power to the analogue audio circuitry and the digital section used to control the NAC 552. As is usual with all high-end Naim preamps, the analogue output to the connected power amp is via the power supply, carried on the thicker Burndy cable connecting the two.
The control of the NAC 552 may be digital, but this is a purist all-analogue amplifier, with a total of nine inputs – seven on DIN sockets, two on RCA phonos – to handle even the most complex of systems. Two of these can be set to unity gain, for use with a surround sound processor, while one will also provide power to an external device such as a phono stage, and inputs can be individually assigned to the source selector buttons, which also offer a choice of ‘record’ and ‘listen’ outputs.
Within, the NAC 552 takes mechanical isolation as seriously as it does keeping electrical interference at bay; its main circuitboard is on a heavy brass plate ‘floating’ on springs – a feature also seen in the ND 555 network player – with this suspension tuned to a frequency below the limit of hearing.
