A couple of years ago I acquired a Super Pas Three from a friend. He had bought it from somebody else, so I haven't a clue as to exactly what went into the building process. It's definitely an older build. Anyway, it works fine and I like it, and have used it with several different amps all with good results. My understanding is that an output buffer helps provide needed flexibility for these preamps, particularly when using them with solid state amps. Is there a way to know by looking if a buffer was added to mine? And if not, would it be advisable to add one ? What improvements, sonically, might I hear?