Soix posted a link to the papers written by Perpetual Technologies on upsampling vs interpolation. The papers describe their "P-1A Digital Correction Engine" which was plagued with problems from the start that were never resolved after repeated promises by the manufacturer.
If you do an internet search on google.com for Perpetual Technologies, you'll find a handful of product reviews and in more than one review from different magazines, you'll read about how the reviewers P-1A didn't work quite right. A search on Audio Asylum will also reveal several owner complaints about the Perpetual P-1A. Not only was this product plagued with problems from the beginning, the company failed to deliver on promised updates and software revisions.
Their white papers may sound good in theory but the P-1A which they write about, failed miserably in reality. Is the company still in business?
If you do an internet search on google.com for Perpetual Technologies, you'll find a handful of product reviews and in more than one review from different magazines, you'll read about how the reviewers P-1A didn't work quite right. A search on Audio Asylum will also reveal several owner complaints about the Perpetual P-1A. Not only was this product plagued with problems from the beginning, the company failed to deliver on promised updates and software revisions.
Their white papers may sound good in theory but the P-1A which they write about, failed miserably in reality. Is the company still in business?