Resistive loading is really NOT a big issue when it comes to step up transformers. The bigger concern is the appropriate turn ratio and the amount of gain provided by the step up transformer.
I disagree with this statement. The Delos can sound quite disagreeable without proper loading, at least in my system using SUTs. If you pay attention to transients and timbre you get important differences depending on loading. If you aren't tuned in to acoustic instruments (e.g. good classical recordings) you may not notice this as much.