Ah, so you think that tubes are superior to SS? Kind of a blanket statement there...
As for source equipment, if your preamp is good, how would adding a tube buffer help?
I really do see these tube buffers as a solution in search of a problem. If your source and preamp are good, you don't need 'em. If your source is not optimal, adding a tube buffer wouldn't seem to be of any benefit - assuming your preamp is good.
If tube buffers are giving you some kind of benefit, then your preamp is obviously junk - to put it bluntly. 
On the other hand, I do think that buffers for the tape loop on a preamp are a good idea, but few preamps have them.
yes, preferring tube preamps is a blanket statement - one that covers *me* quite nicely, thank you.

there *is* one s/s preamp i would like to check out - the ayre k-1x. mainly cuz tube lovers seem to like it.

not sure if it will ever happen, tho - it's too spendy for me to yust plunk down the cash for an in-home audition, even for a used sample.
re: your other comments about my preamp, & tube buffers being a solution in search of a problem, well, i will yust attribute that to your ignorance. obviously, no experience is inwolved.

thing aren't always as simple or straightforward as they seem, especially in audio.
re: your comment about tube buffers being good for preamps w/tape loops - not sure i can see the difference between using a tube buffer here, vs between source & preamp, other than the fact that it can be switched out when not wanted. but, unlike something like a dbx dynamic range expander, which i find useful only a small percentage of the time - ie: compressed recordings or compressed fm radio - i have never heard a good tube buffer impart anything negative.
ymmv,
doug s.