Its not the same unit. I am not sure whats different but I know they arent the same
It's true, the MP-2 and MixPre are not technically identical. But my ears can't tell the difference and I'd be surprised if anyone else here could. Here's some info from the SD website:
http://www.sounddevices.com/tech/mp2_or_mixpre.htm"MP-2 and MixPre Input Topology Differences
Electrically, the MP-2 and MixPre share the majority of their microphone preamplifier circuit topology. The high-performance Lundahl input transformer is at the core of both mic pre circuits, and both share the same six-transistor discrete output topology. However, the two units differ in how they address the first stage of input gain, which leads to important operational and electrical differences between the two products.
MixPre
Can attenuate a microphone signal completely when gain control is at minimum (off-attenuation is infinity).
Two gain ranges, depending on phantom power position. (s/n 0501_ and 0502_ only)
Phantom Off - off to 66 dB of gain, input clip level at -10 dBu
Phantom On - off to 56 dB of gain, input clip level at 0 dBu
The MixPre is generally used in production applications which need complete fader control of inputs. Its two-stage input gain allows complete attenuation of inputs and a maximum of 66 dB of gain.
MP-2
16 dB of gain with gain control at minimum level.
Single gain range from 16 - 66 dB of gain, input clip level +4 dBu
The two-stage input gain of the MP-2 allows it to handle input signals as high as +4 dBu (approaching line level!) before clipping. This allows the MP-2 to accept the hottest microphone inputs"