Tube upgrades for Jolida 502B?

I currently am running the EH KT-88's in my 502, to good result. I tend to think that the driver and pre tubes affect things a little more than the power tubes. Running a set of Mullard 4024's in the 12at7 positions, and tung-sol reissue 12ax7's in the pre positions have supplied really nice sound. The bass is not soft in any way-hits a little like solid state. I'm an electric bass player sensitive to that frequency region and I simply couldn't live with flabby bass. Hope this helps a little. -Fish

Thanks to all. Interesting that no one advocated 6550s. I'll follow up once I make a decision and actually do something. Thanks again.

By the way...
A follow up from Michael Allen at JoLida indicates the 502B now comes stock with EH6550s. EH was chosen for "excellent reliability". He said "If you wish to be perfect...look at the KT88s." He also suggested talking to the Tube Store for input on sound qualities.

The full 502B tube upgrade recommendation from the Tube Store was: JJ Tesla KT88, Ei Elite 12AX7E, NOS Mullard 12AT7WA. Any thoughts about this combination? The Tube Store review of the JJ KT88s using Quicksilver amp and Vandersteen speakers is very positive and appealing. Am just a bit antsy about reliability. The Sovteks ain't necessarily the "best sounding" but they are tough. Would prefer to compromise a bit on sonics to avoid blowing a tube or frying an amp circuit component. Thanks for your input. It sounds like KT88 is the way to go and I expect there are a number of options that will deliver very good results as your various systems show. May have to just close my eyes and "jump" as it were.

just fyi if you are interested in my little saga...I went with the full Tube Store recommendation as described above. Just installed them last night. Was only able to listen 1 1/2 hours. I assume the sound will improve further with time. My immediate impression listening to Peter Gabriel's "So" is that I'm hearing some bass notes that appear an octave lower than what I could hear before. Sub-sonic...almost felt more than heard. Greater clarity and more detail than previously. Highs at this point might not be as smoothe as before (I'm actually not quite certain about this) but the original tube complement was 5 1/2 years old. Also the Forests have <150 hours on them. Have to believe more time for tubes and speakers will make a difference. If anyone has thoughts about time for tube "break in"...or whether there is such a thing for tubes as for other components - I'd be interested to know what you think.

12at7 - brimar yellow "t" label 6060s circa 1954
12ax7 - mullards d "getter" circa 1957
6550 - tung sol black plate triple top getter circa 1957

HUGE difference
i like it better now tham my friends mac