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. 

I very much doubt that voltage sag is the problem with a preamp. I have compare 866a tubes with 3b28 tubes, (which only drop about 15 volts and have great regulation) and they sound different, so it can't be voltage sag.

boxsoft

First off, (before you buy anything) do yourself a favor and reach out to Brent Jessee at audiotubes.com, he is the most knowledgeable and best tube supplier out there. He can help with recommendations, and probably has experience supplying tubes for your equipment.

Great tubes are expensive. I can highly recommend the NOS Philips 5R4GYS, and the NOS Mullard GZ37....if they are compatible with your gear. The Philips is magical, and the GZ37 is really close

As others have mentioned, in most gear the 6SN7s have a greater impact on SQ. For NOS tubes (and I can recommend) the 1940s Sylvania 6SN7GT/VT-231 "Black Plates",  and 1950s Sylvania VT-231 "Bad Boy" tubes......both of these will cost you $250 to $300 per pair.

For new production, my favorite is the Linlai E-6SN7s. They can be found for $155 per pair at jjyaudio, which is a very reputable Chinese supplier

First of all, I used a Cary SLP-98P for a couple of years but I got tired of the thick, sluggish sound. I now use a 6SN7 Aikido preamp of my own build, very similar to what Don Sachs was providing before he retired from that business and moved to Spatial Labs. That in turn was based on the Tubes4HiFi SP14 octal Aikido preamp. The Aikido circuit is much "faster" and more transparent than the Cary, plenty of rhythm and pace.

Secondly, I would NOT mess with solid state replacements or different types of tube rectifiers at the risk of voiding your Cary’s warrenty or worse, damaging it. IMHO the Cary sound is determined by the way they configure the 6SN7, and also the type of output caps they use. A lot of folks like that sound but like you, I found it unsatisfying, especially once I heard the Aikido-style preamp.

You COULD try a genuine Mullard GZ34. They tend to be "faster" and a bit more lively on top than most others. A current-manufacture Chinese or Russian 5AR4 will, IMO, NOT get you what you are looking for.

If you want to keep the naturalness and linearity of the 6SN7, I’d suggest a used Don Sachs SP14, or the Linear Tube Audio MicroZOTL or the new Velo, if that’s more within your budget. Also look at the Icon Audio Pure Valve. Another option might be the Black Ice F360, which also uses the 6SN7. That’s my .02. ;-)

ETA: I forgot to mention that the Tubes4HiFi SP14 is still available, and at a very good price. It’s not as tricked out as the Don Sachs version, but it’s a VERY good preamp for the money, one of the great bargains in high-end audio IMO.

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).