Better tubes than factory installed tubes on the Rogue Audio Perseus Magnum Preamplifier

First of all, are you using a tube or SS amp? And do you still own Focal speakers?

For tube recommendations, it depends on the characteristics of the sound you seek.
As a former Perseus Magnum owner, Amperex will provide an airy top-end with great bass and incredible soundstaging. A neutral sonic signature, look for the Heerlen, Holland factory tubes. Also, Phillips Holland ECC83. Amperex Bugle Boys are a premium tube with deep 3D imaging.
RCA Cleartops have very good detail with high-end extension; Siemens as well, and they sound more natural to my ears.
Telefunken is an excellent tube for detail and high-end extension. (but very costly).

A great classic sounding tube is the RCA Blackplate. It’s warm, very open, with smooth highs and good dynamics. There are so many
variants of this 12AU7 Blackplate that they can range from sounding laid-back to very dynamic. The 5814A is open with very good top and bottom extension, while the RCA 5963 is very dynamic with more air on top.

If your system is bright or lacks warmth, you can use these premium NOS tubes in the Gain stage, and a warmer or less detailed tube in the Cathode Follower position. That’s what makes the Perseus so versatile, you can really tweak the colour of the sonics. I always bought NOS tubes in matched pairs, since the cathode followers don’t have to match the Gain tubes.

Brent Jessee explains the different brands and their sonic signature.
http://www.audiotubes.com/12au7.htm

You have to decide what type of sonics you are looking for as a whole from your system.
At this point, your Perseus needs to burn-in for many more hours (I’m just guessing 200 hours). Right now, you’re not hearing the true sonic signature of the preamp. The stock tubes will burn-in at about 60 hours, but the capacitors, power supply and internal parts will take longer.

I can tell you that Telefunken tubes have detail and extended highs which you may not like once your Perseus and amp become a cohesive unit. From my experience as an owner, the Perseus is a pretty neutral and detailed preamp by design. It casts a wide soundstage and the bass goes deep.
With that said, I wouldn’t put 4 detailed tubes in this preamp. For starters, try NOS tubes with good overall balanced sonics, and then let your preamp burnin for a few weeks.

I also found that the stock tubes were terrible and replaced them immediately. But, I wasted a lot of money on tubes that didn’t work well with my system. I bought tubes with extended highs (RCA Cleartops), but my speakers reproduced detailed highs and they were not a good match.

You could try 2 Telefunken's in front, but then you would need warmer, less detailed tubes in the Cathode position. I used to experiment like that. It's worth a try.

If you call or email Brent Jessee and tell him what pre, amp, and speakers you have, he can make a recommendation.
I think 4 RCA 12AU7 Blackplates would be a good start and they are reasonably priced.
From his website:

12AU7 RCA blackplate, Old Logo, or made for organ brands. Fine 1950s vintage tube:

A nice USA 1950s tube that was widely used in organs and hi-fi units. This is the original 1950s RCA black plate that will never be duplicated. This is probably the last time they will be offered at this price. Good supply now, but when they are gone..... Warm blackplate sound with a nice top end. MATCHED PAIRS ARE JUST $50.00.

I hope my comments have helped. Good luck and feel free to ask for more advice about this very nice preamp. Wait till you hear and feel the bass.