Tube Buffer

Despite using balanced XLR output from DAC to Peachtree Grand Pre, I find digital harshness remains until I engage the Peachtree's dual 12AU7 tube buffer section. However, the Grand Pre sucks as an analog preamp and needs replacing for that reason. I love the functionality of the Musical Fidelity M8Pre, which also has a good phono section, but I fear that as a solid state device it will simply pass the harshness down the chain. Rogue Audio RP7 is a tube preamp which would presumably kill any digital glare, but has no phono stage. The Rogue RP5 is a lesser device overall, but does include a phono stage plus, of course, tubes. Questions: (1) sonically, how much better is the RP7 than the RP5 (considerably, according to TAS)? (2) Does there exist some relatively inexpensive tube buffer device which can be placed between DAC and the solid state M8Pre? Really not in the market for an outboard $2k phono preamp.