I haven't heard the SSP 75, so I can't really comment. I have heard the SSP 25, 30 and 50 though. I felt the 60 bested all of them in terms of warmth and lower noise floor. Possibly due to the outboard power supply. I listen to 80% music and 20% HT. I wouldn't consider trading in my stereo preamp for a SSP unless I was at least 50% music. I like my set up the way it is. I find that during movie watching, I am visually distracted, hence audio is not as critical. A Denon receiver does fine for this purpose. Also consider that these SSP upgrade at a dizzying pace. Meaning if you lay out long green for a SSP 75 today, in two years you'll either have to spend another couple grand to bring it up to date (if possible, some manufacturers don't upgrade) or sell it for less than half what you paid for it and get the newer, current format. These SSP's outdate and depreciate faster than digital gear. I spend 90% of my money on 2 channel. In a couple years, I can buy the latest $1000 Denon receiver. I look at them as disposeable. I used to be into the high end SSP's, for years I owned Proceed, Aragon and Classe SSP's, I'm much happier now.
Besides, my CP-60 has a very nice built in phono stage that no SSP can match.