Which preamp to buy?

I have a Krell KSA 250 amp and Thiel 3.6 speakers. I am looking for a matching tube preamp with a volume control. I am willing to spend about 1,500 (used). Can you please recommend some premaps? I listen to jazz 70% of the time.
Someone has a 17LS conrad johnson for sale on this site. "LS" is the Line Stage designation-. They are asking $2250. not as low as you mentioned. This is a great combo cj and Krell. There are several other of their pre's for sale here. One, I think 12B (BLACK) which is also a good match.
Good luck, and good listening.
Along the conrad johnson line-up you may want to consider a used premier 14. It is closer to your price point than the 17 and is highly rated comes with remote. As Larry mentions if you can stretch your budget the 17lsI is great as well.

Preservation is the key word here, to preserve all that is good within the system while gaining in the areas you feel are it's weakness.

With your equipment, you probably need a preamp that warms the sound a little (particularly for Jazz).

I would suggest a Cary SLP-88, available well under your price limit. Another option would be a Rougue 66.

I agree with the others with the c-j 17LS recommendation. Well worth the additional dollars!

Good Luck!*>)
And now for something completely different. I don't subscribe to the "all Krells are bright,(etc.)". I think the KSA 250 might even be a bit warm. If you want to balance the sound that attracted you to the KSA 250 in the first place with some tubes, I suggest a Sonic Frontiers Line stage. A very neutral tube stage that has a low output impedance, is DC coupled (Krells rightly or wrongly are reputed to be sensitive to DC offset), offers true balanced inputs and outputs, a nice remote and is built as well as a Krell. BTW, I've been using c-j pre/power on Thiels for many years.
VTL 2.5 or 5.5. Both are currently in production, VTL seems like it is going nowhere, and the two units sound very good. The 5.5 is a great piece and the successor to the great VTL Ultimate preamplifier.
For what its worth, I paired an earlier CJ preamp, the PV-10, with an Aragon 4004 SS amp about 10 years ago when I bought my present system, after hours of A/B tests with tube and SS amplification at the dealer. The Aragon amp is a lesser-powered derivative of the more famous 8008BB designed by a former Krell engineer. The combo drives B&W 801 Matrix speakers. The system performance jumped dramatically when I had the CJ subjected to a full standard mod including the highest quality passive parts, tubes and work on the power supply. Then I had the same thing done with the SS amp with further improvement. I haven't tested the modified preamp against any current CJ model which would cost much more than the total of my PV-10 plus mods, because I haven't felt the need to. In fact, on a cost/value basis, I began to wonder if a good audio technician could accomplish more for my system than swapping out older equipment for newer.
I really love my Audible Illusions Modulus 3A so much that I was thinking of buying their first; an AI M1 that just went up for sale. Whatever, an AI M3A is a step in the right direction. It takes much more bucko's after that.
I am using a Krell 2250 w/Thiel 3.5's and a VTL 5.5. The 5.5 is quite good w/excellent bass control. It has remote volume, mute, phase inversion, and HT bypass. I previously had a Krell KSL (I still have it) and I really like the detail, warmth and "creaminess" that the VTL has added. There is a used one at Upscale Audio. Of course, your source will also have some effect on this. Good luck. I think you are really on the right track.
If you can find a PSE HL1 it is much better than the VTL 5.5. You can usually buy for around $1,200 or so. Dean does and upgrade to this also which takes the HL1 to a league that only the top preamps can beat.