It depends on the voltage being provided by the current supply. You need a power supply that matches the voltage of the current supply and meets or exceeds the current rating. Matching the voltage is very important in this case because the preamp doesn't have any onboard regulation.
If you look at the picture of your power supply on the previous page, you'll see that the current power supply has a transformer providing 18v-0-18v at 0.16 amps. To the left are 4 diodes, there's a resistor and two 2200uf/35v caps. Below the 2 caps, the cable connecting the power supply to the preamp is connected to the board by 3 wires. One is carrying the positive rail, one is the negative rail and one is the ground. You'd have to measure each to figure out the voltage needed, but it's probably around 15 volts.
You're probably not going to be able to use an off-the-shelf solution.
You can get a regulated board on ebay (like this one; assuming the voltage output is correct):
https://www.ebay.com/itm/Ultra-low-...215744?hash=item2ee5f02340:g:2mIAAOSwLqFV8pxF
And a toroid like the one here:
https://www.parts-express.com/avel-lindberg-y236503-160va-22v-22v-toroidal-transformer--122-615
And a case:
https://www.ebay.com/itm/Full-Alumi...461917?hash=item2134d78b5d:g:RuQAAOSw0e9Uv1AT
So, that's $200, if you're handy with such things or you can get someone to put it together for free. The question is whether the juice is worth the squeeze.