Tube buffers?

I recently used a Bottlehead Quickie as tube buffer. The Quickie is a two input preamp, not a tube buffer exactly, but in my system it was run strictly as a tube buffer between my Resolution Audio Opus 21 system and amp.

I sold the Quickie after about six months and regret it now. In my system it's pretty simple to swap it in and out as I can use a balanced out directly to the amp and RCA out to the Quickie and then more RCA to the amp.

I'm going to build another Quickie and put it in when I feel the urge for a little tube sound. Just gotta get around to ordering one, very simple to build.

The more compelling reason to own a tube buffer, is to help give component hooked up to "see" an impedance you want the component to see. I am not an EE or anything close, I hope some one with a clearer explanation to chime in. In my system I have used certain buffers to aid impedance mismatches. Almarg please...
The one thing people think they are buying is a "tube anywhere in the system" will tubify the sound. It may make your system sound differently but if you really want tube magic you need to use a tube power amp out. People will stamp their feet and say they get tubbiness by using a tube pre, but they just don't know they are missing. Tube magic is an incredible 3D imaging that is very hard to duplicate when a tube signal if flattened out by an solid state output stage. It took me almost a decade to finally get it right in my system.

08-22-15: Mechans
The more compelling reason to own a tube buffer, is to help give component hooked up to "see" an impedance you want the component to see. I am not an EE or anything close, I hope some one with a clearer explanation to chime in. In my system I have used certain buffers to aid impedance mismatches. Almarg please...

Yes, that will often be the case. This thread provides a good discussion of impedance matching, in the context of line-level analog interfaces. As I said therein:

07-11-12: Almarg
Ideally the input impedance of the amp should be 10 or more times greater than the output impedance of the preamp, at the frequency for which preamp output impedance is highest. Otherwise audible frequency response irregularities MIGHT result.

If, as is often the case, the highest output impedance of the preamp across the audible frequency range is not known, and only a nominal output impedance is specified (perhaps based on a frequency of 1 kHz), I suggest using a ratio of 50 or more, and preferably 75. Many tube preamps, and some solid state preamps, use a coupling capacitor at their outputs, which can cause their output impedance to be much higher at deep bass frequencies than at higher frequencies.

Impedance incompatibilities are most likely to be encountered when using a tube preamp with a solid state power amp.

If the power amp has an input impedance of around 47K or more, it is unlikely that there will be an issue, even with a tube preamp.

A tube-based stage will usually have a high input impedance, which is in the direction that may be helpful. If it is intended to be used as a buffer, it will probably also have a low output impedance, which would also be in the direction of being helpful. But the opposite might be the case, with respect to its output impedance, if, for example, it is a tube preamp that is not specifically intended to be used as a buffer.

Based on my experience, I agree with all of your (Mechans) comments regarding tube power amps and preamps. Although of course opinions on that will differ widely. And of course many speakers will not be good matches for tube power amps.

Regards,
-- Al