I originally owned the Musical Fidelity X10v3 with outboard power supply and Revelation Audio umbilical cord. This added a bit a warmth and musicality in front of Channel Island D-200's ... which some have characterized as somewhat dry. The downside on the MF X10v3 is that it doesn't allow for tube rolling. There is no ability to tune or select tubes to complement your system.
I looked at the Grant B283 and Yaqin from Pacific Valve, settling on the Yaqin as it allows one to use NOS 6922 and 6DJ8 tubes. The Grant does not. Next, since I wanted to be sure of getting the right sound and the right equipment for MY system, I ordered the Yaqin and the Audio Horizons TB 5.0n at the same time. Bottom line ... it matters less what the most expert A-goner says about this because ultimately it's about YOUR system and your tastes. Both allow for a 30-day in-home audition with refund less nominal "restocking" fee (what a crock). Yeah, it's B.S. - but worth it if it helps make a decision free of looking back and second guessing. In the meantime, I boned up on tube information (Joe's Tube Lore is a good place to start).
It didn't take 30 days for me to determine that the AH TB 5.0n was the clearly superior product that justifies a significantly higher price than the Yaqin/Grant. I sold the MF X10v3 for a decent price and returned the Yaqin. Overall, I've been happy with the AH Tube Buffer. Of course, YMMV.