Looking for 5AR4 rectifier tube most like solid state

Thanks for all of your suggestions so far, and don't worry carlsbad2, it's not a troll. Here's a bit more background:

Decades ago I had a top-flight olive Naim system with Royd Albion speakers, and I discovered that PRaT is a crucial element to me, more so than tonality, soundstage, etc. I enjoy all those other things too, but not at the expense of rhythmic engagement.

I eventually started building my own solid stage power amps, and have moved entirely away from Naim gear. I still demand the same rhythmic qualities from my systems, though. My main system has the Klipsch Cornwall IV, which I love for its ability to handle fast transients and create a sense of scale and "being there". As is often the case with the Cornwall, it's up against the wall. This makes the soundstage less 3D, but again, I don't mind that too much.

One day I was listening to my system, and I felt that it was a bit "thin" sounding, and I wondered if I could scratch this itch for more tonal richness, I was strongly encouraged to get a tube power amp (or integrated), which would purportedly do a much better job with the Cornwall IV. I acquired the Cary SLI-100 integrated, and I enjoyed how it sounded. It retained the rhythmic drive that I need, while also filling out the sound.

However, it bothered me that I couldn't use the many power amps that I had built. Amongst the earlier conversation encouraging a tube power amp, some urged that a tube preamp with a solid state power amp would do just as well or better.

I tried the Cary SLP-2002 with some of my amps, and I preferred that sound, and I was able to resume with the fruits of my DIY labors. Much like the SLI-100 integrated, this preamp from Cary had strong rhythmic strengths.

Then I got the opportunity to get the SLP-05, and took the plunge. I was disappointed to discover that it sounded so laid bad. It was spectacular in most respects, but completely boring rhythmically. So now I'm trying to determine if rolling tubes will get more life out of it. 

It comes with eight Electro Harmonix 6SN7 tubes (2 input, 4 driver, and 2 headphone). I just tried a pair of EH Gold for the input tubes that I had, and that boosted things a bit, but we're up to perhaps 20% of what I want.

Some of my research has suggested that the rectifier tube will have the biggest impact on handling of transients, although some posts above refute that. Regardless, I've arrange to pickup a Mullard GZ34 5AR4 (with either the 4 or 7 notch plates, I haven't decided). We'll see what it does.

After that, I'm not sure how to proceed. I could try switching off the 4 driver tubes as well, but some comments above suggest that what I want isn't possible from the Cary SLP-05. 

Thanks, all, for your recommendations! I’ll start with that NOS Mullard, and decide whether to continue and swap the driver tubes, or to give up and move to another preamp.

FYI, the Mullard is an F32 4 Notch dual halo GZ34/5AR4, Coded F32 B3C1 (Translates to Blackburn plant, 1963, March, 1st week).

Thanks for those recent responses. I haven't got that Mullard rectifier yet (picking it up this weekend), but someone came by with some NOS Sylvania 6SN7 GTB. That was a big boost forward, beyond the Electro Harmonix (Gold in the Input, and regular in the Driver).

It's getting closer to "good enough". We'll see if the Mullard takes it over the finish line. Otherwise, a pivot to another preamp may be required.

@immatthewj The argument that the rectifier is not in the signal path is incorrect. The rectifier helps to supply the voltage that's used for the output rail. Noise or dips on that feed are going to affect the sound. Smoothing capacitors certainly help, but they will not eliminate all artifacts of the rectification stage.

With my solid-state Class-AB builds, I've gotten better sound by changing from a TO-220 Schottky FWB to a superior SMD Schottky FWB, so I know it's possible.

What I'm not sure of, however, is whether it will improve the handling of transients. I believe that has much to do with the unit's ability to communicate the rhythmic aspects of the music. Keeping my fingers crossed!

Yes, I was a bit surprised when they claimed that changing the rectifier would require a complete power supply redesign. I've designed power supplies for many solid state amps myself. SS rectifiers have a lower voltage drop, so the rectified voltage would be higher. Consequently, the smoothing caps would have to accommodate the higher voltage.

I guess that higher smoothed DC voltage would be passed along to any regulation circuits, and potentially require more heat dissipation. (I have no idea what's in place in the SLP-05.) If there is no regulation, then the higher voltage would be passed along directly to the rest of the circuitry.

Therefore, I wouldn't feel comfortable trying a SS rectifier without the blessing of Cary.

Thanks, @br3098 . I haven't had a chance to try the Mullard yet. If I'm still dissatisfied with that, then I'll ponder whether to try a plug compatible one, or to start looking for another preamp.