Transformer and $200 ($300) amplifier update

Because of the requirement to power two Soekris boards instead of one, I need a new spec for the R-core transformers and can no longer buy off taobao or ebay. Its now $65 per transformer from what I can tell (ouch) when custom-made to be:

30VA Transformer: 30/(12.5VAC + 12.5VAC + 12.5VAC + 12.5VAC + 4.5VAC) = 30W/54.5VAC = 0.55A per channel.

I then plan to use the five rails in this fashion:

+/- 12V bipolar supply (left mono channel):

• 12.5VAC to +12VDC Left Channel
• 12.5VAC to -12VDC Left Channel

+/- 12V bipolar supply (right mono channel):

• 12.5VAC to +12VDC Right Channel
• 12.5VAC to -12VDC Right Channel

3.3V digital supply:

• 4.5VAC to 3.3VDC isolated I2S rails, toslink module

Also, the amp's price will increase by $100 but this will give me the perfect excuse to call it the Spartan. Perfect!