I've never heard of the DSP-Xtra processor, but it sounds much better than whatever 100.3 was using before.
The DSP-Xtra is made by Broadcast Warehouse in London. It is a very good processor that holds its own with anything currently available. KZQX has used their processing products for quite a long time. We originally had an Orban 8000 that I found on eBay (money was tight). Somehow I stumbled across BW when they were developing their first product, the DSP-X. We were a Beta Test site with serial number 004 in service for a long time. We both learned a lot from the experience, but it was positive for both of us. I'm quite sure it is one of the reasons KZQX-LP sounded as decent as it did. I guess my philosophy is "you don't have to sound small, even if you are small."
The DSP-Xtra includes an Arianne Leveler, which is one of the most amazing compressor/limiters I've ever seen (I've been involved in professional audio most of my life). While there are many good products out there, this one is certainly worth your consideration, assuming you need such a product.