Try some of the new TechTubes from the updated, old Mullard Blackburn England factory. These are wonderful!
The important issue is noise. you can only really use tubes tested for noise and microphony, by a really good reliable dealer RAM tubes are famous for this. As is Upscale and a number of others. Whatever flavor you decide upon they above all else must be quiet in a phono gain stage or in preamp gain stage.
The new or current production tubes are more often quiet tubes with no micophony than old stock but not as good sounding tone wise. The German tubes are known for being quiet and hatend to have a clean fast signal.
If you can afford good quiet ANOS Teles I would give them a roll.
The former Ei made a tube so lively and shiny it was called the silver bullet. Too thin for me but a fast sparkler, as the name implies. To get them now you must buy them as NOS tubes and believe it or not they aren't all that easy to find.
The current production, Russian Tung Sol gold pin for a straight forward sound leaning only a tad to the warmer side, has rich mid bass tone.
Haven't tried the New Blackburn tube yet but it seems to please those who have.
A brighter sound was part of what made the Shuguang 9th ed. or 12AX7C special. Yes I am serious and you can't find them any more. The B ver. or 8th ed. is what is being offered.
As noted above, well tested, low microphonic tubes are required in a phono amp. better tubes can help, e.g. Siemens of Telefunken, but an 834p will never sound detailed or clear, at least, not without extensive modifications (with which I have no experience.) Lush and smooth, yes (in my system, too much so, just as you suspect.) But you have ss amplification, maybe it balances out. An 834P is a good place to start, but looking at the rest of your system, it is not up on the same level.
If you want to put more money in to it (that you probably won't ever recover) and I think you would be far better of getting the coupling caps replaced and maybe a couple of other parts swapped out. Mitch the service tech for EAR USA has been doing these parts swaps for years and with the right parts you can get rid of the overly lush presentation. I think that is the more effective way of doing what you want compared to tube rolling, but I can't see it is the best from a economical point of view. You might be better off selling it and trying a different phono stage.
We added a EAR MC-4 to our 834P, switched it back to MM and were blown away by the improvement.
The built-in step-up transformers defiantly leave something to be desired, but then again we doubled our cost.
There are lower priced alternatives, see www.10Audio for a DIY step-up.
You might want to try a (lower gain) 5751 at V3. This allowed us to turn our volume control up a little where our preamp sounds better.
The sound might even out with the B&O rig.
I use Mullard tubes in my 834P Signature.
When using a MC cartridge I would suggest a higher spec external step-up transformer for the MC input. I run a Fidelity Research FRT-3 that levels out the lush bass and brings out the highs a little for a really enjoyable performance. My cartridge is a Dynavector Karat 17D3.
This is a great phono-stage non the less.
Dont bother with still-points of other accessories. The mechanical construction is more than adequate for proper support.
I have a modded 834p deluxe. I use GE 5751 black plate silver clip in the first position closest to the front. Of all the tubes I tried, this tube gave the best extension on both ends and the best bass by far, not really a choice. The middle and end tubes took a bit longer to find a match. I was told by EAR that these positions are the left and right output tubes, but one is NOT for the right and one for the left. 1/2 of one tube is for the left, and the other half of the same tube is for the right, ditto for the other tube. This allows for a sonic blending.
I tried many combinations and settled on Sylvania black plate 5751 for the back position, and a Mullard cv4004 for the middle. The sylvania brings the vocals a touch forward with a wonderful midrange, and the Mullard has very nice extension. I could go on trying different combos for years, but at some point you say that sounds great, stop listening to the tubes, and start listening to the records again. I just recently added 2 of Herbie's "sonic stabilizers" to the top of the EAR, and was quite blown away with the improvement, the next day I ordered 2 more for my Cary slp-98. Highly recommended.
I currently have the stock tube in the V3 position (cathode follower/output stage) and NOS 1960's Amperex Bugle Boy 12AX7's in V1 (gain stage) and V2 (gain/RIAA equalization stage) positions and it sounds excellent. I tried some NOS 1960's RCA Command series 5751's in the V1/V2 positions and it sounded great too! The Bugle Boys have the soundstage depth and finesse of the 5751's with a touch more extension/sparkle in the highs and better bass extension and noticeably better midrange (which I've found that's where Bugle Boys in either 12AX7 or 6DJ8, excel at).
Happy listening to you,