The voltages can be checked with a multimeter. The guy uses WIMA caps, so he's not cheaping out on components. He's not likely to miswire it as his ebay feedback would guarantee no future sales. The thing that would keep me from getting one would be a moral decision (and the fact that I have both a blue box and a rack mount already and I can make my own). Even if the voltage does prove to be outside the desired range, given that there are trimpots, it does seem like that problem could be easily rectified (pun intended).
The only reason that it couldn't be checked by a multimeter is if the circuit were so badly implemented that the load of the bass electronics would result in an unacceptable voltage drop. Given the amount of effort that has gone into the design and construction of the box, it's highly unlikely that this would be case. You'd have to flail pretty severely or build the thing with an intention to make people sound bad to end up with that problem. The solution to this issue is easy. If you aren't comfortable with the box or don't like the moral implications, don't buy it. If you want to take a shot at it, roll the dice. It doesn't seem like a very high risk. It pretty much does come down to an emotional decision since if you are going to take the chance, it seems foolhardy not to doublecheck the voltage. If it checks out, the risk is essentially nil and you'll have a cheaper alternative. If it doesn't, you've dodged a bullet and you're only out the time and money it might take to make it right. As I stated before, I would apply similar caution to any power supply that didn't come directly from Santa Rosa, regardless of the name on box.
