Wasting money. Over the years tried a couple and did nothing to improve the sound. If you are looking for a tube sound then buy a tube preamp. A buffer will not do it.
I wanted to think a cheap ($250) tube buffer could help with the sound from digital stuff. I bought one and was disappointed.
I ran into a cheap (for me) tube preamp i bought to try as a 'glorified tube buffer. I bought a VAC Standard ($4K list, I paid $1,400) and it works great as a means to solve the problem of digital crap.
Now I am very happy with my digital gear as it all goes through my bigger than average tube buffer.
Or you could just buy a power amp like the Rogue Audio Medusa that couples a high-quality tube input stage to a Hypex output stage and get great smooth musical sound with low noise and high power while not having another box and more cables to deal with... The Medusa replaced the Wyred 4 Sound STI-500 in my system. I'm listening to it right now as I write this (Hugh Laurie's 2nd jazz album) and it's better than fantastic. Happy Holidays!
The problem with a tube buffer is that it can only alter the sound. Essentially, its an EQ with 1 setting. It can't add anything. It just covers up problems areas in the music/playback system that some people find pleasing. If you use one and like it, that's fine. That's what really matters. For me, however, I prefer matching my components in such a way that I don't have to resort to using such devices. Its more work, but I think its worth it.
In most systems, some, if not all problems, can usually be traced back to the preamp. Instead of getting a line level device like a tube buffer to "enhance" the sound of the preamp, I say just get a better preamp. Elizabeth's example is interesting. She attributes her VAC preamp to acting as a tube buffer and thereby giving her digital that she can listen to. Looking at it that way does makes sense. To me, though, it looks like she's describing the sound of a good preamp. Either way you look at it, the preamp is definitely the piece that's making it all work. (And maybe the brownies.)
If I had to generalize, your electronics are known for more of a "clean/detailed/dry" presentation rather than one that is "full/round/warm". If the latter is the sound that you prefer, then I would look at replacing one or more items in your electronics chain to achieve that goal, rather than adding something additional.
OK, initially I wanted to stay out of this discussion; but I see that on 12/28 the OP asked specifically about the Audio Horizons tube buffer. I own the TB 5.0, with upgrades. Designer Joseph Chow customized it into a combination tube buffer and TP 8.0 phono preamp. In other words he put two boxes into one.
A little history: despite a few negative opinions I embarked on the tube buffer path some time ago ... first starting with the low cost Yaqin, then Music Fidelity X10 (?) and finally settling on the AH 5.0 tube buffer. With the first two, there was some improvement, with the AH 5.0 offering the kind of flexibility (via tube rolling) and sound quality that I was seeking. I have it placed between solid state pre/pro and Channel Island monoblocks. IMHO this tube buffer is not only quiet but also fairly transparent.
I've owned this unit a few years now and can only see upgrade to AH TP2.x series - a tube preamp with HT bypass. Right now the main obstacle to making that move is purely economic. It will be interesting to see how much improvement results from installing the Audio Horizons flagship preamp versus the tube buffer. I will be pleasantly surprised if the improvement is significant. In other words I could live with the SQ as it is; but we always want that extra 2% ... don't we?
Audio Horizons has a limited trial program. Or you could purchase outright and see how you like it in your own system and in your own listening environment. In the end ... doesn't that count a whole lot more than what others have to say?
DISCLOSURES: 1) I am the "Strateahed" listed among the testimonials on the Audio Horizons website; I have no financial interests or other incentives from the company; I wholeheartedly stand by my statement(s).
2) Had I known more about the HT bypass option available from some tube preamp manufacturers at the time, I would have likely gone that route instead.