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

You may want to take a look at Decware in East Peoria IL. There is a very good website. Steve has an exceptional preamp that is reasonably priced. All hand made with point to point wiring and lifetime warranty although you will probably never need to use it. Also many of his amps have a volume control and are very good without using a preamp. Good luck!

Whitestix - Is the Shuguang Treasure CV-181-Z a direct replacement for the 6SN7 in any circuit that uses that tube (I have a DeHavilland Ultraverve which uses one 6SN7)?

I was speaking with Jeff Wells of Wells Audio, at length, earlier tonight. Turns out that he has two preamps coming out this summer which he said would produce world class sound paired with my existing Wells power amplifier. I think, at this point, I'll probably wait to check those out before I purchase anything else in terms of a preamp. At least barring some miraculous deal on one of those discussed here.

My sincere thanks to everyone for their advice and recommendations, all information is greatly appreciated. I've done a great deal of research based on the input and am well armed for making a preamp decision when I pull the trigger. 

I'd like to respond to jmcgrogan2's post (my computer will not let me cut & paste in this forum). The Cary SLP-05 output impedence, per their published specification is 400 ohms. The input impedenace of my MAC MC 302 is 22k ohms (much less than the "OP's" 50k and certainly less than the manual's 30k), While the MAC's 22k ohms are perhaps less than desirable for ease of "driviing" the amp, the SLP-05 has NO problems at all and I've got more power than I could ever use .... volume levels remain well below the half-way mark on the SLP's volume control pot and that is VERY loud.

Tak1, the concern regarding the rise that I cited in the SLP-05’s output impedance to 3400 ohms at 20 Hz (per Stereophile’s measurements), from considerably lower values at higher frequencies, has nothing to do with volume. That kind of impedance rise at low frequencies, btw, is not at all uncommon among tube preamps, and occurs as a result of the output coupling capacitor which the majority of tube preamps use.  (The impedance of a capacitor rises as frequency decreases). The concern it raises is that in the deep bass region, especially in the bottom octave, some degree of rolloff and/or undesirable phase shifts may occur, if the load impedance is too low.

A rule of thumb that will assure that no such effects occur is to apply a factor of 10 to the 20 Hz output impedance, which in this case would mean a load impedance of 34K or more. That does not mean that a problem would necessarily occur if that criterion is not met (it depends on how the output impedance **varies** as a function of frequency); it means that a problem won’t occur if that criterion is met.

Also, the audibility of any rolloff or phase shifts that might occur will vary among different systems depending on the deep bass extension of the speakers that are being used. And also depending on whether or not a subwoofer is being used.

As I said in my post that John (Jmcgrogan2) referred to, "30K would be somewhat marginal (or worse) for use with several of the preamps that have been suggested." Personally, I prefer to avoid component choices that might be marginal in some way, when good choices are available which don’t have that concern. Also, John makes a good point about the fact that the benefits of the SLP-05’s balanced architecture would not be fully taken advantage of if it is used with an amp providing only unbalanced inputs and having an unbalanced internal signal path.

Regards,
-- Al