Thank you.....could you be a little more specific??
Harman Kardon's DPR line was always noted as plagued by apparent quality control problems, as you've noticed first-hand. The AVR has been known to have its quirks as well, but less severe and universal.
The DPR 2005's power rating is at twice (0.15%) the distortion of the AVR 635 (0.07%). I'm positive that neither is audible, but that is a source of a little of the DPR's extra power. I have not yet found measurements that I could use to compare the power output of the two units, so I cannot really expand on this further. Do you already have the AVR 635 and does it seem to be performing well-enough in terms of power?
Harman Kardon's MSRPs are always fantastically inaccurate. By the time the DPR line was discontinued they were actually relatively close in price (it dropped to ~$500 during clearance if I recall correctly) and they both sell for nearly the same amount used.
The AVR 635 has an additional component input, more digital audio inputs (one extra optical and one extra coaxial), and it otherwise has all of the same processing capabilities. It is, however, bigger, likely runs warmer (due to its more traditional power supply and amplifier setup), and is not nearly as pretty on the inside.