I haven't listened to either the C350 or C320BEE, but have had an NAD C340 for a couple of years (now being used as a preamp with a higher rated power amplifier) and can comment based on that, because the C350 is an uprated C340, the C352 is an uprated C350, the C320 is a lower-rated C340, and the C320BEE is an upgraded C320 that has the same power rating as a C340. These appear to be closely related designs, with some differences from model to model. All have toroidal transformers, impedance sensing circuitry, NAD "soft clipping," preamp-out circuits, the same general layout and configuration of controls, and power ratings between 40 and 80 watts/channel RMS into 8 ohm loads. The C340 is rated at 50 watts/channel, the C350 at 60 watts/channel, the C352 at 80 watts/channel, the C320 at 40 watts/channel, and the C320 BEE at 50 watts/channel. The C320 BEE and the C352 appear to be upgraded with multistage power supplies, better quality volume controls, and a few other circuit tweaks; the C352 also has an IEC power cord that can be replaced with higher-quality aftermarket power cords. The reason that NAD has been able to ring all these changes on the same basic design is simple. The basic design is a good one that offers genuine value: a moderately priced solid state integrated amplifier, designed in the UK and manufactured in Asia, with a balanced, musical sound on the warm side of neutral; reasonable clarity, detail and smoothness; and good headroom based on power reserves capable of delivering short-term peaks well above the rated power. All are good matches for comparably priced source equipment, such as such as NAD or Cambridge Audio CD players, and reasonably efficient bookshelf speakers, such as psb or B&W bookshelf models, so they provide a good basis for moderately priced systems. All do well with moderately priced interconnect and speaker cables, such as Signal Cable, MAS, Audioquest or Kimber. All are also capable of performing reasonably well with higher quality source equipment and speakers, so they can continue to anchor systems of increasing quality. The upgrades to the current C320BEE and C352 models apparently have audible sonic benefits compared with the prior models, but the prior models were quite good to begin with. I am currently using a C340 as a preamp with an NAD C270 power amplifier rated at 120 watts/channel, and a Cambridge Audio D500 CD player, to drive Vandersteen 1b speakers, using MAS interconnects,Signal Cable speaker cables, and a Cardas power cord on the CD player, and the sound of the system is very enjoyable. Higher quality (and higher priced) equipment would probably offer incremental improvements in imaging, soundstage, detail, clarity and smoothness, but NAD integrated amplifiers are a good place to start and provide the flexibility to support a growing system over a multi-year basis.
