So here's an interesting twist: The windings on my Gamut A came loose, so I put my Spiro Solo E&A back on with Gamut guts on top. This seems to be getting a much better volume balance than the full Spiro Solo set. Previously, when I'd used the full Spiro set, the upper strings were projecting noticably louder than the lower ones. So either the Spiro D&G are just really loud on my bass and the guts less loud, or else the lesser tension of the guts on top enables the Solo E&A to project more. Either way, it's a nice mix. I did a recording session today and the bass sounded nice and balanced. The lower strings blended well with the guts, and the bottom was full. I had done one session with the full Spiro set and the low strings sounded wimpy. Of course, different studio, different mics, different engineer, so it's hard to be scientific. There's so much voodoo with upright bass, different strings and different tension. It can make you a little nuts sometimes!