Are there any $1500 tube preamps that that can compare with Tubes4hifi's SP14?

As someone who builds tube gear and owns many pieces from various manufacturers, a couple pieces of advice when buying tube gear.
1 Understand the tube being used.  Look at the tube data sheets.  Look for high transconductance, greater than 6500 ohms 
2 Build quality is paramount.  If AC heaters are not done right your signal to noise ratios will be poor
3 Older products may needs rebuilt.  Many of the large capacitors go bad after a 20 years
4 Stick with a 9 pin tube as they provide internal shielding.  Unless it has a good DC heater supply
5. Do a little research on what a SRPP, Mu Folllwer and White Cathode folllower is and what their pluses and minuses are
6 Finally the quality of parts is paramount.  Poor undersized caps can lead to poor frequency response.  Carbon resistors color sound

As to passive preamps a good transformer volume control costs but they are very transparent and have plenty of drive as the excess voltage is converted to current.  With a tube preamp your minimum gain will be 20 which is 20 more times than your amp needs.  Which means the rest of it will be burned across a carbon pot.  Unless a good stepped attenuator has been used

BTW my main two amps are a parallel SET 300b and a 845.  I also have a MC225, a VT100, Sophia Baby Amp, and a Unison Reaerch 845.  Just to say I am not against tubes.

Hi, 
I disagree with the statement that tube preamps have a minimum gain of 20.  My Line Stage has 10 dB of gain and some active preamps have only 6 to 8 db of gain. 

9 pin tubes are the most common choice for preamps however 8 pin (octal) are excellent candidates as well. For example the 6SN7/12SN7.  My preamp uses a 4 pin tube  (DHT) 101D  and it's superb IMO. It always boils down to implementation when all is said and done. 
Charles 

"I think I’m most interested in the imaging and the details on the highs. Theres a little muddiness in the midrange but that’s not bothersome."

Of all the components, your current preamp is the strongest piece with regards to the above qualities. Your amp is a bottleneck, and most likely your source is too. One mismatched component can wreck your systems imaging and details.

Of the 9 pin tubes the 12au7 is going to give you the lowest gain which when setup properly will be a gain of 17 to 20.  This is where looking up the tube data sheets come in handy.

http://www.mif.pg.gda.pl/homepages/frank/sheets/093/1/12AU7A.pdf

A gain of 1 will be a cathode follower or amtube buffer.  Tube like the 300b, 845, and 2a3 will have a gain around 4

Mudiness in a system with decent components can easily be caused by the room.  The book How To Get Better Sound is an excellent resource. Running test tones through the system (30, 50, 100, 200, 500, 1k, 2k, 5k, 10k, 15k at a minimum) will help you map the room.   A poorly designed tube preamp may de-emphasize the low frequencies, due to the undersized coupling cap, thereby reducing the the amount of excess bass in the room.  If you have already mapped the room and added diffusers and absorbers where necessary you can ignore this.

Sfall and Ajcrocker1 those thoughts raise a couple of questions then on how to think about this. My thinking was this.  The leap between the Mod Squad and the Audible Illusions in sound quality was monumental.  It changed the experience entirely. I love what I'm hearing.  I want to improve upon it and try to get a little better imaging and detailed highs.  I don't really think about anything as a problem to resolve so much as improve on what I have.  I assume it would be just get an even better tube preamp.  I thought that the preamp had such a huge influence  that it would be the piece to continue to build upon.  So, if I was to swap out the preamp I have or the amp that I have, I would think a 1500 preamp vs. a 1500 (I could go up to 2k on that because the Bryston I wouldn't keep) amp would get me the bigger reward in improved sound.  I don't even want to know how Tidal's sound with the node compares to cd or high def digital.  Tidal is too much fun and I don't want to have a knock in my head against it because it will drive me nuts!  I have to see about what improvements configuration can contribute here.