Conrad Johnson owners -

I currently own the CJ CT6 preamp and I am looking to upgrade to either the CT5 or the LS16II. Is there anyone out there that has heard both of these in their system or can tell me if there is a sonic difference between the two.
Is there one that you think is better and why?

I don't own a c-j tube preamp yet but I have been reading up on them. My understanding is that a CT5 would probably sound more refined and more neutral than your CT6 (I don't know how much more) whereas a 16LS2 would have a warmer, more golden sound, which some people like and some people consider colored and less transparent.
The 16LS2 preamp was a trickle down design based on the original Art preamp technology. I own a CJ power amp but have never heard either preamp, but I believe that Tom's response is accurate, at least from everything I have read. If I had to choose between the 3 of them, I would actually go with the 16LS2. I have also read that the CT5 sounds awful until broken in, which supposedly takes a very long time due to the teflon capacitors used.
I have owned the prem16 and demoed both the CT5 and ACT2 series one.

Both the CT5 and ACT2 have a nice tight bass and extended high's in comparison to the prem 16.
However the prem 16 IMO is one of the great pre amps with great rythmic drive, reasonably extended bass with excellent dynamics. Treble is a little warmer (a good thing IMO) than CT5 and from memory the soundstage is larger.

Overall the prem 16 is more musical, holds the tonal qualities of instruments better and would be my pick.

BTW, I was actually thinking of going back to the cj prem16, however a nice s/h cj ART came up recently and I snapped it up.
I have owned the CT5 and CJ LP70S combo for 12 months or so. I think Tomcy6 is spot on.