All that I know is that my 48-in-1 that I bought from Excellentcom.net (or whatever their name is) had OBVIOUS sound issues, particularly the "death" noise that occurred when you die in say, Galaxian, Scramble or Super Cobra. Based upon what I paid at the time, which was a LOT more than what these boards go for now, I would have to ASSUME that it would be considered an "A" board. This was before the Arcadeshop board was well known, and I probably paid comparable money to what that board costs.
Later on, when the 60-in-1's came out, and Nixs started selling them here (I wanted to buy one), I voiced my concern about sound issues. He assured me that if I was not happy, that he would take back the board. I told him about how the sound issues with my 48-in-1 made some of the games difficult to play. He assured me that I would be happy, and his shipping was prompt.
When I received the 60-in-1, it looked JUST LIKE my "old" 48-in-1. In full anticipation of Galaxain being fixed, I fired it up, only to find out that not only was the "death" explosion noise was still the same (static +10 DB higher level over all other sounds in the game), but also that the shot/fire/missle noise was completely MISSING! Needless to say, this was a step backwards from the 48-in-1, and Nixs graciously took the board back just as he said that he would. I do not blame him at all, as he is just the middle man. But this experience has really put me off to the whole "This isn't the poor quality 'B' Board" versus "This is 'A' quality" statements. They are all made in China, and provided that they actually "work", I really don't think that anyone would/should care WHICH factory in China built them. What matters FAR more to me, however, is whether or not the games play as they should. And in my book, I have yet to find ANY multi-board (outside of the Arcadeshop.com board) that accurately re-creates the original arcade experience.
Nixs is a good guy, and he obviously delivers on his promises. This post is not intended to reflect poorly on him, as he treated me right. And I am kind of sorry that I even brought it up earlier in the thread. But if you look at MY personal experiences, then I would HOPE that you can understand why I have to shake my head when people try to distinguish between the "quality differences" of a PC board that costs well under $100 new...
Lee