[Spridle]

Thanks brucek, Terri and Wayne. Your comments are very helpful. My best course of action at this point will be to just try it and see how it sounds with EQ on the mains. I will be careful to use low Q, small cuts and focus only on a few areas. I think I will dial in and test with REW and then listen for about a week.

But the way Wayne, I researched the Rane PE 17 before I bought them and, as you note, I would expect them to be superior to the PE 15. Believe me, I could not tolerate anything that noticeably degrades the sound in any way. The specs on the 2 units are significantly different. For example, 98dB S/N on the PE 17 exceeds the theoretical maximum 96dB of 16-bit CDs. Here are the comparisons of the two units (maybe you could comment on these specs since you have experience in the recording industry):

PE 15
Freq Resp.: 15-33kHz +0/-3
THD+Noise: 0.02 ±.01
S/N Ratio Boosts/Cuts centered: 92±2dB at unity gain

PE 17
Dynamic Range: 120dB (20-bit equivilent)
Freq. Resp.: 20-20kHz ±0.5dB
THD+Noise: 0.005 ±0.001 @+4dBu, 20-20kHz, 80kHz BW
S/N Ratio Boosts/Cuts centered: 98±2dB at unity gain