Any suggestions on Tube Buffers?

I have an Onkyo P-308 M-508 amp/preamp combo that I'm quite pleased with but am curious to wet my feet in the world of tubes. Anyone have any experience with this? I was thinking about a Grant Fidelity M-283 tube buffer between the amp and preamp. I know it's not a full blown tube setup but maybe it will give me a little taste of the magic. I really don't want to have to take out a second mortgage. I will be driving Polk SDA-1B speakers. Any suggestions would be appreciated.
I've been curious about and researching the same thing. I believe from what I've read that the GF M-283 is the same unit, but priced higher than the Yaqin CD2 buffer. You might want to try the CD1 which is the high end version of the CD2. It can be found brand new on ebay for about $125.

Give us the update if you decide to try one out!

You should aslo check out the Decware Zbox tube output buffer from Decware.
I saw the 283 on their site for $125. Honestly though, all you are doing is "messing" with an already clean signal. Personally, I'd consider a tube pre instead to get a better taste of tubes. I don't think a buffer will give a real taste. It's simply going to softenwarm up the sound a little.

Save for a pre
I agree with above post. I owned an EE minimax BBA, arguably one of the better buffers out there. Inevitably you will be adding another component to the chain and purposely coloring the signal (or compensate for it, depending on how you want to look at it). In the end, I found the resulting sound was more veiled and bloated in the midrange. Removing the unit was akin to hearing what sounded like a 'purer' signal. If you want to wet your feet the right way, I suggest a reasonably priced tube preamp.
I'll sell you my Musical fidelity 3 for $200 + shipping...
This is pretty funny actually. The purpose of a buffer is to compensate for incompatibility in impedances between components, the input impedance of a buffer being very high, and the output impedance being very low. I know that it is obvious, but that is why it is called a "buffer", not a makeyourhifisoundtubeywhatzit. It is a very useful device if the driving source has a higher output impedance such as inexpensive CD or DVD players that use op amp based output stages driving inputs of highish input impedance or long cable runs. Presumably, your preamp and amp are matched, so better sound does not come from adding a set of interconnects and an active device between them, a cheap active device, with a minimal power supply to boot. My best advice is to save for a nice tube preamp. They come up on Audiogon frequently starting around $300.00. If you like it, you will be able to sell your present preamp and recoup a substatial part of your investment and probably end up in a pretty similar place cost wise. And yes, I actually own a tube buffer, but do not use it. Just my two cents.
In the above post, it should say......"driving inputs of lowish input impedance", not highish input impedance. Of course.
Viridian makes an excellent point! that is the primary reason for a 'buffer' - tubed or otherwise. In fact the BBA I alluded to stood for Buffer Booster Amplifier, and was made specifically for impedance compatibility. a common use for this is between a device of high output impedance to one of low input impedance, like a SS amp. You'll need to know specs to determine if this is the case for you.

The sound benefits in theory are fuller sound and non-rolled off extremes (characteristics of impedance mistmatch) but beyond that, there is an alteration in sound from the unit itself, impedance matching notwithstanding.
I must agree with the growing consensus on this thread. I would save for a tube preamp. I owned a Musical Fidelity X10v3 tube buffer, with the external power supply, and although I liked it for a period of time, I ultimately removed it from the system. It never wowed me like many tube preamps have.
I've been searching a little on Agon and found this thread with some people that have real experience with a buffer. It's all pretty positive.
I've tried earlier tube buffers and they don't reflect true tube audio.These products just seem to dampen harsh or hard digital characteristics.A true tube preamp will give you a start of what tube audio is.Going with a tube power amp will really put you in tube heaven that tube purist mostly seek.
I just wanted to point out that I believe that there really is no difference of opinion here. Ryan has linked us to a thread where the OP is using a receiver and Denon CD player, probably the most appropriate use of this type of device as mass market CD players usually have OP amp output stages. I am sure that the buffer makes a good bit of difference in this application.

Later in the same thread a poster links us to his review on e-opinions and lists an inexpensive Sony CD player in his system.

Finally at the end of the thread, another poster reports good results with a Sherwood Newcastle receiver and a DVD player. This is the perfect application for a buffer, but whether the improvement comes from the fact that it is a buffer, which can be tube or solid state, or whether it is tube based is unknown.

I can report that in higher end, well balanced systems, the level of detail lost using my X-10D and X-PSU power supply is not worth any second harmonic glow added to the presentation IMHO.