Before you invest $600 for tubes, you might want to consider upgrading the SLP98P itself to F1 status.
You have asked this question before. The simple answer is to roll them.
Based on my largish experience rolling 6SN7s, I am confident you will find an big improvement over the Sino stock tubes.
If you are real queezy about the bucks try some less expensive alternatives. Email me with you preferences and I can tell you a reasoinable bit about what's out there.
Some excellent notes of the 6SN7 family of tubes(and their presentations), most of which I can verify from personal experience, having tried all the top contenders: (http://home.att.net/~chimeraone/6sn7sound.html) Contact Kevin at Upscale regarding the Popes. (http://www.upscaleaudio.com/Pope-6SN7GT_p_105.html) He'll never steer you wrong, and his quality control/testing/matching is exemplary. BTW- The 6SN7s in your Cary are used as buffers, and a quad of bottom gettered Sylvania 6SN7GT/VT-231s, from the 50's (ie: http://cgi.ebay.com/Sylvania-6SN7GT-Bad-Boy-Tubes-Matched-Pair_W0QQitemZ260453877957QQcmdZViewItemQQptZVintage_Electronics_R2?hash=item3ca442c8c5&_trksid=p3286.c0.m14) would serve you well, at somewhat less of a price. I'm not vouching for that seller, as I've never purchased from him.
thanks for the suggestions, much appreciated.
I had never heard of Pope tubes prior to about a week ago when I searched tube rolling on the Cary SLP98 so you must be thinking of someone else. I like my preamp a lot, I am just wondering if it's worth $600 or should I move up to the SLP 05 and get a seperate phono stage?
I may try rolling the tubes first.