Actually they do have tubes in them. The tubes run with a VERY low plate voltage, and so they have a REALLY long life, with regular use. And unlike Lucas electronics (all you Triumph, MG, and Jag fans out there know what I'm talking about), these Brit-made electronics are VERY reliable and are great performers!
Musical Fidelity gear is really nice-sounding, and if your system tends to sound a little cold or analytical, throwing one of these tube buffers between your preamp and amplifier can really help warm up the sound.
I've heard this unit, and it can sound REALLY sweet in some systems.
Personally I think MLs sound VERY nice when there are some tubes in their supporting electronics chain, be it in the preamp, as a buffer, or the amps themselves.
You can get these on EBAY and AUDIOGON all the time, but generally they are not discounted much. I guess the demand for them keeps their resale value high...
Several members here on the forum are using Musical Fidelity gear in their systems, and seem to like the sound. YMMV.
The only way you're going to get "tube sound" using only solid state gear is to run Carver or sunfire gear--that stuff is "tweeked" to sound convincingly tubey. I should know--I've owned a boatload of Carver gear over the years for just that reason.
--Richard