I'll check the manual which I haven't looked at for a while to see what's said. I don't think the power switch is wired for independant rails but I'll check. What's happening in my pic is not just more voltage. The 2 batteries are connected directly to ground and not floating across the resistor voltage splitter circuit so it's not just more voltage I'm after but a stiffer and better balanced supply. Doesn't look like those links are doing it like this. Just checked, the manual doesn't address it as independant rails and the power switch would need to be replaced to configure it that way. Also, as you change the voltage the splitter will be become less balanced. Generally not a big issue as long as there's enough on a leg.
I personally think the basics like a stiffer supply and lower output impedance are more important than a fancy chassis or different opamps though there's nothing wrong with that either. I also don't like the idea of not having an input coupling cap as one of those links has done. I would instead keep that one and once I knew my supply would stay balanced, work on the resistor values to lower the output DC which is already not bad. Removing the output cap and resistor should be a better mod than removing the input DC blocking cap though nothing basically wrong with either. Here's where a regulated dual rail supply might help even more.
Looks like they have upgraded a lot of parts in those links. I like it cheap and cheerfull and used a couple things that I already had around but it's nice to know there's a lot of versatility here in terms of circuit and parts. I wouldn't mind having a slightly larger 470mF output cap for very low impedance loads but think the basic parts values and quality are quite good. It really is a nice modding platform because it has a lot of potential.
Edited by goodvibes - 11/10/12 at 10:22am