FWIW I implied something similar, based on roughly similar reasons, but didnīt turn it into a pissing contest, just restricted it to the OP apparent needs
The board manual only says "10 - 15V DC power supply, 500 mA min."Didnīt even mention 1A but was happy that it would take 500mA or lessThen it can be fed by a 7815.
You need at least 3V more than +15V feeding the 7815, including ripple, so aim at some 20/22V DC RAW to account both for ripple and drop under load.
If you can get a 15/16VAC transformer, rated 1 to 1.5A, it will be perfect, so you donīt need more than, say, 22/25VA .
All of this is very conservative, the board may not even take 500mA by a large margin, if a "500mA supply" was suggested.
And on the other side suggested reducing Raw Voltage input to decrease dissipation .
On the other side, understand JMAFīs position very well, very often walk away in disgust from other Forums (wonīt mention names) when TV couch "designers" steer some poor OP straight into the quicksand pit and boo boo my efforts to save him ... oh well.
Just not here