Best tubes for sonic frontiers power 2?

What is the best sounding tubes for SF power 2?
6550-Svetlana,Tung-sol,Electro harmonics gold,Sovtek or
Genelex gold lion KT-88. Is KT-88 better than 6550?
I am using Svetlana 6550c right now.
If its sound better but is it reliable?
and What is the best input tubes? I got Sovtek 6992.
IMO most folks who post asking about tubes that 'sound' better are really unhappy with some aspect of the sound of thier unit, i,e, too bright, boomy bass, rolled highs, etc. It would be much more productive if you would post about how you percieve your present sound and how you want to change it.

FWIW, 6550's and KT88's just sound different. Lot of folks like KT88's more but a lot depends on amp design, speaker design, and personal preference, mostly the latter.

IMHO the most rugged and relatively neutral (albeit with a bit of softness in the highs) 6550 is the SED aka Winged C (=C=) made in St Petersberg and in the 90's was sold under the brand Svetlana. Present day Svetlana's are not the same tube. The SED is an excellent tube and is often OEM.

Sovtek's 6922's are rugged and usually very low noise tubes but they are noted for sterility more than anything elso. Very few folks prefer their tone, at least in amps or pre-amps.

Gold Lion re-issues are gaining a good user response - but, unlike many KT88 brands, I'm seeing very few folks comment about 'excessive' mid-range warmth. It seems most user comments have focused on extension and clarity in both frequency extremes.

Thank you,
MacCormack transport,Belcanto dac3,Rega Apollo.
TUBES: Sonic Frontiers line 2,Sonic Frontiers Power 2.
SOLID STATE: Adcom gfp750,Mark Levinson no.335.
CABLES: Straightwire Serenades,Analysis Plus.
Which 6550's should I use? What is better than 6922's?
If your amp will sound 'better' by using 'better' tubes, how in your mind will the 'better sound' sound? Fuller, warmer bass; tighter bass, deeper bass; warmer mid-range, fuller/faster mid-range; warmer upper mid-range, smoother highs; crystal clear and extended highs?
Will the KT88's make my SF power 2 sound warmer and smoother highs compared to 6550c's that I'm using now?
I am thinking about buying 2 quad set of Gold lions re-issues
or Tungsol 6550 re-issues.
Ellyjr, First a caveat - I've never heard a Power Two in my home in my system. I have used and still own its predecessor, a SFS 80 as well as its larger brother the SFM160 the predecessor to the Power 3.

I used Sovtek 6550's, GE6550's, SED6550's, Sovtek KT88's, SED KT88's, Tesla EL34's as well as E34L's om this amp. It initially came with KT90's and 7308 tubes. Big bass and good lower mid-range, but a bit cold and clinical in the highs. I next went thru the EL34 group. I liked the SED's but the power was halved and I needed the whole 80wts. The Tesla's were more lively in the highs but in the long run, for me tiring.

I boiled down my selection process for power tubes to 1) SED 6550's which produced a tight/deep bass and remained linear thru the mid-range (but it was not 'warm') and slightly soft in the highs, and 2) SOVTEK KT88's which had a warm but fairly clear mid-range, was a little rolled off in the highs and the deep bass was not as 'present'. But a very nice, relaxed sound. I have found both of these tubes very rugged. The Sovteks are very cheap, BTW.

Next I played with a lot of small tubes. With the SED's I liked both the EI6DJ8's and Tesla6922's. The former are clearer and more tonally neutral - the latter were a bit softer in the highs and 'fuller' in the upper bass. Ultimately I selected the SOVTEK KT88's and used EI small tubes.

I subsequently got involved with a different amp which was close to ideal for me with SED 6550's except with my other stuff the upper mids were a bit uneven and after 2 years of playing with different types and different brands I ended up with the SOVTEK's again - same sonic signature I detected using the SFS80. Note that in a different amp the SOVTEK sonic signature was the same BUT it had a totally different effect on the amps sound, i.e. enimic bass, too soft in the highs, and a loss of a sense of dynamics.

In response to your questions - Will KT88's make my Power 2 sound warmer and smoother. Answer - Maybe warmer, maybe not smoother. Will the GL KT88's make my system warmer and smoother - maybe smoother, probably not warmer than good 6550's.

What would I do if I were you? Start with just some new production (inexpensive) small tubes and see what they do you your present system. In general the JJ's will give you a slightly warmer upper frequencies and fuller bass and the EH's will give you a fuller/deeper bass and extended highs (and in mystuff a sense of a mid-range suck out). If you can find EI's, one of my favorite tubes, you will get an excellent/neutral response that is anything but clinical or warmish.

Once you have gotten a little experience playing with the small tubes you can start considering the power tubes. Eventually you will find a combo you will prefer.

The cheap/quick solution if you don't want to go thru the process. I'd get some Sovtek KT88's and some JJ6922 and live with it for a year or two and see where that takes you.

Hope that helps a bit.
I will start with the driver tubes first. thank you
How about the SF line 2 pre, it sound a bit lean compare to my Adcom. I have 6922's any other tube you can recommend? Thanks Again
I've never heard a SF Line 2 nor do I really know what demands it makes on its tubes, either by way of ruggedness or noise. If noise/ruggedness is not an issue try the same tubes I mentioned as possibles for your amp. If noise and ruggedness are issues for you, the only reasonably priced tube I have used (in my ARC SP10II) is the NOS Reflector 6H23EB which is not a warm tube, only marginally better than old Sovteks (I think much better however than the newer Sovteks).

FWIW, in case I've not already said it, get your initial experience rolling tubes by using current production stuff, not expensive old NOS tubes so highly recommended. That can be a tar pit for the unwary.
I changed winged Svetlanas for the new Tung-sol 6550's in my Power 3's and they are a much better tube all around. Better low end definition, smoother mids and extended, sweeter treble. A significant upgrade and I was surprised that a variant power tube of the same type would have made such a difference. I am very partial to the KT88's as well as I think they are a little "sweeter" than 6550's, but I never tried them in the Power 3's.