two 9v ac adapter with different mA's

The 500mA can supply up to 500mA and the 800mA can supply up to 800mA. If your load is less than 500mA you could consider them interchangeable for most practical applications. Tom

Yepp, but where was the original post?

If the total load is getting up close to 500mA I would be a little skeptical of using the 500mA supply without some additional filtering. It just might cause some problems. Seems like those adapters give some cushion so they don't have to strain under the load.

Pj

The original post is quoted in its entirety. There would be no filtering, the OP said it was an AC supply.

Tom

thanks guys--for some reason the 800 did not work for my dc guitar amp which has the 500mA supply. The plug seemed to have fit though--wonder what happened?

Even if the plug fits, the plus and minus may be reversed if the output is DC instead of AC.

Your original post said "AC" adaptors. If they are DC instead my answer may have been a little different.

Center plus or center minus? Regulated or filtered? No load vs. full load voltage?

Regards, Tom

yeah sorry, both are AC to DC adapters--i thought that was implied by the word "adapter" but I guess I was wrong. Sorry, I'm not too familiar with this stuff.