Hey Mate, I would have thought $275 USD shipped was an ok price (Pete what do you recon ?) as long as it's in good condition. The MC-1 is compatible, it's the pedal the units shipped with I'm pretty sure. You can then use a 7 pin MIDI lead (hopefully that's included with your MC-1) and you plug the power adapter into the "phantom" power input on the back of the MB1 and the additional 2 pins in the MIDI lead power the MC-1, nice and tidy, no power adapters at your feet
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I agree about the 16 awg cables, seems a bit overkill for line level signals and, as you say, you'd usually use good quality shielded inst cable. As long as the cables are shielded the additional thickness will probably improve the bass response a bit although this starts to get into a hotly debated topic (cables) in the audiophile world. Thicker cables can carry more current. The physics is interesting as transmission down a cable is largely an edge phenomenon (or so they say) so more edge area better transmission. Bass however tends to go down the centre (thus some speaker cables have a solid copper core to improve bass response). A guy I know spent $6,000 AUD to get 2 x 1 meter (~3 feet) RCA <> RCA cables made in the UK for his hi fi. Then, to a large degree it get subjective, some say they can here the difference. Back to an earlier question, what cabs are you going to use ? Are you going to be able to run the MB1 in stereo ? as that WILL make a difference (that I'm sure you'll like).
Anyway, it seems like the majority of us here, you've got the ADA bug