Used it already in my previous OTL tube amp build, now again. Not sure if it affects sound that much or is it just the circuit itself, but microdetails are at a previously unimaginable levels to me. This solder isn't that shiny and polished like standard ones, but look is not important inside I think.. when cooled down, it's just some grey and matte material, no fancyness. However, 10% silver content is a good promise. Only thing you have to bear in mind is a slightly higher soldering tip temperature needed to melt this solder + clean the tip more often than usual for a nice, clean job - there's no resin whatsoever mixed to the solder. The amp I bulilt with that solder sounds freakin' amazing.