I don't think you could lose with either one. I haven't heard the Cambridge 840Av2, per se, but I've heard the 640A fairly extensively and was impressed. Haven't heard the NAD c372, but the Internet is rife with favorable reviews.
I think you should also look at a contender that adds a little twist, and may be more satisfactory when you migrate it to line level use--the Peachtree Audio Nova. It's a little more money, but in the basic neighborhood (about $1200). It has a little less power (80wpc), but it adds some interesting twists--a tube-driven line stage and an excellent built-in upconverting 24/192 DAC. It accepts USB, two toslink, two coax SPDIF digital inputs plus three analog stereo inputs.
I did hear this unit and it was under extraordinary pressure--it was at a high end store's open house to demonstrate the Wadia iTransport and the upcoming Magnepan satellite panels and separate panel woofer. Source was an iPod docked to a Wadia iTransport, plugged into a coax SP/DIF digital input on the Peachtree, which served as a DAC and line stage to tri-amp the Magnepans.
The combo was stunning. This demo would have fallen apart if the Peachtree had been deficient as a DAC or as a line stage. But it had incredible speed, clarity, musicality, extension, and a subterranean noise floor. If anything, the Peachtree's DAC and linestage shined as much as anything I heard that night, which included some *very* expensive gear in other demo rooms.
I think you should also look at a contender that adds a little twist, and may be more satisfactory when you migrate it to line level use--the Peachtree Audio Nova. It's a little more money, but in the basic neighborhood (about $1200). It has a little less power (80wpc), but it adds some interesting twists--a tube-driven line stage and an excellent built-in upconverting 24/192 DAC. It accepts USB, two toslink, two coax SPDIF digital inputs plus three analog stereo inputs.
I did hear this unit and it was under extraordinary pressure--it was at a high end store's open house to demonstrate the Wadia iTransport and the upcoming Magnepan satellite panels and separate panel woofer. Source was an iPod docked to a Wadia iTransport, plugged into a coax SP/DIF digital input on the Peachtree, which served as a DAC and line stage to tri-amp the Magnepans.
The combo was stunning. This demo would have fallen apart if the Peachtree had been deficient as a DAC or as a line stage. But it had incredible speed, clarity, musicality, extension, and a subterranean noise floor. If anything, the Peachtree's DAC and linestage shined as much as anything I heard that night, which included some *very* expensive gear in other demo rooms.