I have the SSP CT, CP-47.5 and CP-50.
I first used Krell HTS 7.1 as a pre-amp for my OPPO 105 Full Modwright upgrade. The Krell is the unit that made me learn that a pre-amp is necessary for Amps. The OPPO Modwright without preamp sounds not good enough. It is not “not bad”. It is “not good”. The Krell opens the door for me to enter the preamp world. The HTS 7.1 has really good analog section. I bought two used ones and that’s how I like it. However, I inquired a SSP CT (SSP 800’s more rough-looking brother). I play piano (with Yamaha C7, amateur level) and violin and listen to Symphonies and Quartets and Piano in Davis Symphony Hall and other theaters and churches. I have a good sense of what real instruments sound like. With that feeling, I think the Classe plays musics (classical ones) better than Krell. But Krell plays movie sounds better. Or say, Classe plays musics more truthfully but Krell plays sound effects with more realism. I listen to music more and therefore I saved my SSP CT and sold one Krell. What left to my second 2-ch system was the Krell HTS 7.1.
Next, for 2-ch system, I started with Classe CAP151 ( after numerous Denon receivers and some 5-ch dedicated amps with Denon receivers), I realized that the CAP ‘s preamp section is not as transparent as Krell. For the same “more musical” reason, somehow I still prefer Classe’s sound. That’s why I began searching for a dedicated Classe preamp. Luckily I score one CP-47.5 on eBay. Upon trying the first time, I immediately heard the improvement from CP 47.5 over Classe’s build-in preamp. I was still using CAP 151’s amp section, which 151 allowed. Obviously, next I would think of upgrading the amp itself. Score a good priced CA151 on USAudiomart. The CA151 matched 47.5 pretty good. Now the CA151 and 47.5 bundle had better sound to enjoy. 47.5 has better instrument separation and sounds clearer and has deeper sound image. Then recently, scored a CP 50 on eBay with $550 plus $65 shipping. Got it by impulse. After several day's listening, feel extremely satisfied with the sound. It sounds very different from 47.5. The sound seems more pure, clean. The improvement on the cleanness is like going from USB to adding a DDC. I had a Denafrips Pontus II first than added Denafrips Iris later. With CP 50, it is like adding another layer of DDC. Then, the Bass, yap it definitely bloomed. I thought I did not add the right filters for my Vandersteen sub while listening to 47.5. The CP 50 brought out the bass. Overall the sound feel more solid and crispy from CP 50. This verified what I have read from on-line where people praised CP 50 against CP47.5. I also saw one review that preferred 47.5 i stead. But on my system, the CP 50 is an obvious winner. I use Celestion SL 600si. Too bad the nice sounding speakers need good amp ( and preamp) to sing. Guess that’s why Celestion did not survive in the competitive world.