You should try a passive attenuator between your CDP and preamp. This Schitt Audio SYS will tame down the aggressive output of the CDP. For a mere 50 bucks it is worth a try!
Some of the most enjoyable music was with a system i had with a Cary SLP 93 preamp, Cary SLM 100 mono blocks (100wpc) and ProAc response 2.5's. Probably 9 years ago now when I had all that. Proac's and tube just seem to gel the best imo. You should really try a tube amp IMO.
Also like was mentioned tube rolling in Cary gear is quite effective. I also ran NOS Mullards in my preamp and they are fantastic tubes.
The 89db of the ProAc's is not that bad as they are a tube friendly load. I had success with 60wpc, 100wpc and even a 40wpc tube amps with my old 2,5's
I am by no means an expert on any of this, but you have 3V of output from your CD player and an input impedance of 300K ohms for your amp, which I think indicates that you could run about any preamp you choose.
I cannot explain why the Parasound sounds so loud as it has less gain than your Cary preamp.
You could try a passive preamp, so the prior suggestion about the W4S STP is a good idea. I had that preamp and it was pretty smooth but not the most dynamic thing I have had in my system.
A preamp with a lower gain like the Primaluna Dialogue Premium (10db) might work for you. I still own this preamp and it has good bass and vocals are well articulated in my system.
I also run a Conrad Johnson LS17-2, which does not have the organic bass of the Primaluna, but is more nuanced and "alive" in my system.
I guess my message is that a preamp is critical and we all need to keep listening to as many as we can.
Hopefully, someone more knowledgeable about gear responds to your post with more experienced answers to your question(s).
Thanks for listening,
The JC-2 gain is only 14db at the maximum setting and you can turn it down to 4db so that is not likely the source of your problem. Also the input sensitivity for your amp is 1.8 volts which should easily accommodate the JC-2 at maximum. In fact the gain on your SLP-03 is higher at 16db. Easy thing to try is if you have an unused pair of SE cables around change the CD to preamp from balanced to SE and see what happens. Your CDP is putting out 6 volts with the balanced outputs as opposed to 3 volts via SE.
I think you are on target to suspect source. I use Roon core server because it sounds better for streaming and because there are a lot of discs that are mastered too "hot", cause DAC clipping distortion. Roon allows you to reduce digital loudness before the DAC, avoid clipping distortion. I doubt you have that control with the Cary CD player.
Cary SLP-03 pre-amp is a wonderful pre-amp and sounds very musical! That is the word you need to know, very musical. Differences between tubes can be easily heard through the SLP 03 because it is sensitive enough to reveal different tube; that is a big plus! It is well designed and constructed with a serious power supply. The unit weighs 25 Lbs. For me it replaced an ARC 25 MKII (5500 dollars) and is more musical sounding than the ARC. The ARC weighs a lot less. The Cary needs a good platform along with good footers. Hook up the very best cables that you can afford, Power Cable & Inner connects. It is a balanced component, so to get the very best out of it, it should be at the very least used with a balanced amplifier! Synergy is a must in audio !!!! With good speakers and some tube rolling, you should be in heaven. One more tweak is required; it needs a VPI Brick on top where the transformers are! Happy listening.