I have auditioned both the speakers . Pioneer with Denon AVR-1912 ( long ago) and Dali with Denon AVR-x2000. To me, both can't be compared as both are in different price range with Pioneer as entry level and Dali as mid range. You will find that people have upgraded from Pioneer to the speakers in Dali class. For entry level Pioneer is better than Polk T50, Taga Azure and Jamo s426 etc. On the other hand Dali Zenser 7 has an edge over similar price speakers and lots of FM are happy with performance. If budget is not a constraints then one must go for Dali Zenser.
Pioneer have sparkling mid to high frequency with tight and agile low end. But certainly they need to be backup by good subwoofer for fuller sound. Due to low sensitivity, they need powerful amplifier. Average looks and build quality. They are discontinued from pioneer products line so difficult to get service or spares.
Dali Zenser 7 have very detailed high frequencies response with great vocal presentation . Due to bigger bass drivers they are faithfully producing better low end than Pioneer. At high volume I found them to be bright and brittle. Build quality is great and still available in market.