chorus, hopefully this may help some in your now continuing search. I'll say upfront I don't agree with all the comments made here. But then this is the internet. ;^)
I owned Duntech Princess for 19 years. That tells a great deal about how I felt about them. During that time I had three friends who also owned that model so heard them in a variety of rooms and with various electronics. I've posted about them previously on Audiogon as well as the Speaker Asylum. I also had personal conversations with John Dunlavy three or four times.
John had an engineering degree and played acoustic bass. He began in audio with his Duntech speaker company in Texas. His first model was reviewed and purchased for reference by Burt White, noted reviewer for Audio magazine. I never learned why but John moved to Australia, redesigned his speakers (tall columns with WMTMW configurations), and began manufacturing a number of models there. They became successful, with world wide sales. I bought mine in 1990. The problem was due to the size and weight for most models, shipment was expensive, particularly to the US which was his biggest market.
So John returned to the US to begin building a new Duntech model in Utah which could be sold at a lower cost (mainly reduced shipping). That didn't turn out well and he ended up separating from the company, which remains in OZ. John then formed Dunlavy Audio Labs (DAL) and located in CO. He developed a speaker line up which essentially paralleled his Duntech models, except he cut some costs. He selected different drivers and designed cabinets that were easier, thus cheaper, to build. Sonics were quite similar to the Duntech models although they could be driven with lower power.
The DAL SC-IV was a sibling design to my Princesses. I felt the new model was a very good speaker but preferred my Duntech version. After a Stereophile review of the SC-IV offered positive comments but felt appropriate bass extension was missing for a speaker of that size and cost, John introduced the SC-IVa with improved bass.
As a general statement, both Duntech and DAL offered musical, refined speakers. Nearly all models were large and heavy. Room placement was critical and required distance from both the side walls and front wall. As mentioned, seating distance was necessary for full driver integration with the vertical array. Thus, typically the larger the model the larger the room required. Both lines benefitted from quality electronics, while less power was typically required with the DALs. Driver surrounds (foam) should be checked on any older speaker. The cones should be good unless someone stuck their finger or a screwdriver through one. I can't say if there are any electrolytic caps in the crossovers but that is likely all that might need replacing (same value though). Some folks have modified them but I would caution against that unless you have significant design experience.
A key to John's designs was their time and phase coherency. Changing drivers or crossovers can screw that up.
I still have positive feelings about my Princesses. The only reason I sold them was due to concern over an upcoming move (not knowing what the new room would accommodate) and having a buyer fall in my lap.
I believe if you find any of John's speakers in decent condition and set them up properly you may be delighted.
