@cerberus79, good that you got to the bottom of the problem, even after no longer owning the speakers.
I enjoyed a pair of Duntech Princess speakers for 19 years and would like to clarify a few points here.
John Dunlavy began his speaker business, Duntech, in Texas before moving it to Australia. That company continues in business under other ownership.
His Duntech models were high quality in design, components, and build. John believed in time and phase coherency and based his designs on that. But my Princesses were rated at 90 dB which may have misguided some. The manual recommended at least 200 wpc "for musical enjoyment" and I found that to be true. The best match I found was with VTL 300 monos, and later Parasound JC-1 mono amps.
At one point John returned to the US to begin building a new Duntech model. My assumption was his concern over the high shipping costs from OZ because of size and weight, so a model built in the US could be more competitive. However it was not a sales success and John separated from Duntech to begin another company, Dunlavy Audio Labs (DAL), located in Colorado Springs. There he designed and began building a new line of speakers, based upon their sibling Duntech models. These were the SC series mentioned here by others. The DAL speakers became highly successful for both home and studio applications. So I'm not surprised that your buyer found inappropriate crossover modifications to be the culprit for the poor performance. John's engineering prowess led to the crossover designs which were critical to the sonic success all of his models.
When John's health began failing he sold DAL, but the continuation of the brand was not successful and the company closed after about a year. For those with adequate space and appropriate components I believe both Duntech and DAL models can provide great musical satisfaction, when found used in good condition.