I need a 10 volt AC/DC transformer.?

Here's the easiest solution:

Use the 12VDC output, and put 3 diodes in series with the output. This will drop the 12V down to 10, and give you the voltage you need.

The power draw from an iPod is not great, so almost any common silicon diodes will do just fine.

You may try it if you think your device is worth for the risk. As my advice, it is not good to do so, even though you have the third party transformer with exact 10v output. This because both the transformer and the dockin station may not designed to operate together. Although the transformer output 10v and docking station accepts 10v, both have different output impedance and input impedance respectively. When both device are connected together, impedance mismatch may occur and result in different power transfer as expected. If the power transfer is lower than actual operate power, the device wouldn't function. But if it is higher, your device may destroyed.

Transformer do NOT supply DC, which is what you need.

Not sure about "Protech", cant find them supplying Variable PSU's. Set it 12v, should be OK.

But do a search. One I found, see link.

a 9v transformer will be putting out at least 10v most likely you have the polarity wrong change the leads over as most equipment has a blocking diode inside