I have the Cary SLP05 with ultimate upgrade as well but don’t suffer what you are describing. I find that the Raytheon VT231’s in the gain stages gives the best sense of best solidity. To be honest, I have struggled with understanding this rhythm and pace issue outside of turntables. I have had a number of preamps over the years, tubed and solid state, and feel the Cary is not slow in comparison (recently have had Audio Research and Schiit preamps as well).
Looking for 5AR4 rectifier tube most like solid state
I have the Cary SLP-05 preamp (with the Ultimate Upgrade), which sounds exceedingly good in most respects. Unfortunately, it's sorely lacking in rhythmic excitement (what various British companies call Pace, Rhythm and Timing, or PRaT).
I suspect that the 5AR4 tube rectifier is at least partially to blame. In general, tube rectifiers exhibit "sag". This helps some aspects of the performance, but is likely dulling transients that are needed to create faster dynamics (e.g. percussive envelopes).
Cary has told me that I cannot insert an equivalent solid-state rectifier, as it would require a power supply redesign. Instead, I'm hoping to find a 5AR4 tube that mostly closely behaves like a solid state rectifier. I don't want it to be warm, or smooth, or anything like that. This preamp already has an overabundance of those qualities. Instead, I want it to be fast, dynamic, rhythmic, and exciting, with a real sense of "boogie".
Any suggestions?