Did Digikeijs change the power supply over the years? I don't see any variable voltage capabilities on the ones I have.
The DR5033 and DR5000 I bought all came with MeanWell GST60A15-P1J power supplies - a 15 volt fixed voltage unit intended for HO. An 18v version was also on sale presumable for O scale.
When I bought them the 15 volt versions were becoming scarce so I got some 18v versions and simply replaced the power supply with 15v units. Mean Well power supplies are generally well regarded and I've used them extensively over the years.
These are not variable power supplies and are available on eBay.
Does that help or confuse the issue??
Oldngrey