Best Tubed Preamp For A Warm, Rich Sound, Yet Still Detailed and Agile


As the title says, I am looking for an exceptional preamp (obviously tubed) with warmth and liquidity, some of that golden glow, in the midrange and highs. I do not want slowness, or lack of detail, however. My budget is up to $6,000.00, for a used model. 

Based on my research, many of those that might make the list are very rare to find, and other recommendations would be greatly appreciated. 


nightfall
What amplifier will you be using?

There have been many worthy suggestions, but as Georgehifi alluded to earlier impedance compatibility with the amplifier needs to be considered. Also, compatibility with the amplifier in terms of gain, and with respect to whether both components would be best suited for the same type of interconnection (i.e., balanced or unbalanced).

Regards,
-- Al

Here's a few you may want to adition. VTL 2.5, Aesthetix Calipso, Wyetech Pearl, Lamm LL2.1, Sutherland N1. (I know the N1 is solid state, but I'm still recommending it)
The amplifier that I will be using the preamp with is superb, but not well known, which is why I failed to mention it earlier. It is the Wells Audio Innamorata, which is single ended with an amplifier input impedance of 50k ohms. 
JMC Grogan2, I completely understand your point. I'm trying to find the sweet spot between warmth and richness, without sacrificing too much detail and speed. I particularily appreciate your thoughts as you and I share, I think, somewhat similar tastes. I hope your Rowland Model 6's are still serving you well! 
I hope your Rowland Model 6's are still serving you well!

Actually, the Model 6's are long gone, but not forgotten.

https://forum.audiogon.com/discussions/rowland-model-6-monoblocks-my-thoughts

The Model 6's were some terrific amps, without question the best Class A/B amps I've ever heard.

I have heard good things of Wells Audio, but I've never had a chance to hear any of their products.
I'll be interested to see what preamp you wind up mating with that amp.
Have you asked Jeff Wells for any preamp recommendation?