[quote name='Kiwi' timestamp='1423334945' post='2683710']
I was going to suggest this also. Didn't know aut the piezo optimisation!
[/quote]
Channel B has a higher input impedance, than channel A ( A = 10 Mohm B = 1Mohm- i think this makes it a higher impedance).
I bought my original MB2 (I'm on my second) as I'd read the NS WAV I'd bought at the time required 1MOHM and i wanted to switch.
TBH not sure if optimised was the right word, but it did work very well with the WAV piezo. I had a radial bassbone which dones not have high impedance inputs and it does not drove a power amp very well ( I struggled with my Berg IP, with the bassbone).