Seeking Suggestions on Preamp Upgrade (CJ, Aesthetix, EAR)

Did you eliminate VTL's 2.5 and 5.5?  I've been very happy with the 2.5 for many years with a McCormack amp. Lush and non fatiguing.

Oh my, this question is a delight to which to respond.  I am a long time customer of Don Sachs who produces a 6SN7-based custom-made tube preamp in a beautiful wood cabinet.  By far, it is the finest preamp I have had in my 45 years of having good to great gear.  Don offers lots of options including a remote control, XLR connectors, caps upgrades from Mundorf Silver Oil, Jupiter Copper, to Dueland caps that increasingly enhance the performance of his preamp.  The basic preamp runs around $1800 and betters the performance of preamps many times the cost of his preamp.  Google "Don Sachs Consulting" for more information.  This is my highest recommendation for a preamp.  

HI
Don Sachs here.  I see I have been talked about.   I would love to build the OP a preamp, but he has an amplifier with a 15K input impedance.  I could certainly use a really large output capacitor value and drive that load, but it has been my experience that the sp14 design, while a fantastic preamp, has some issues driving loads less than 30-40K input impedance.  It will do it, but sometimes may not be as dynamic as people want.  I would say this may apply to many tube preamps.  Really, I recommend my preamp for loads of 47K or higher.  It will work with anything, but sounds best with a more benign load.  Any tube amp in the world is 70-80K or higher:)

cheers,
Don

Can't believe no one mentioned Ayre.  (my personal fav)

I'd recommend you investigate the Primaluna Dialogue Premium which I now own. I've owned CJ ET-2SE, Aesthetix Calypso, Allnic L1500, AR LS17SE, and First Sound Presence Deluxe MKII in the past 4 years. If it wasn't for the lack of remote, the First Sound is the most impressive I've yet heard and I would have lived with it long term. The Pirma lacks the sheer dynamics of the First Sound, but is otherwise equally enjoyable. Good luck in your search.
Mike