Just received a QSA Yellow fuse which I am testing in my Modwright PS 9.0 power supply (which only takes one fuse) - see photo. Right off the bat with no break-in it sounds a little more neutral and resolving (but not more natural or musical) than the SR Orange and Audio Horizons Platinum Reference fuses that I've also used in this component. WIll report further after a break-in period. Plan to compare the QSA Yellow against the new SR Purple. The QSA Yellow and SR Purple are each around $200, which is about the ceiling for what I'm willing to spend on a fuse. So I won't be trying the QSA Purple and beyond, no matter how glowing the reviews.
24 hours later ( and 48 hours of playing nonstop) there's been no "mellowing" of the QSA Yellow fuse. Several things stand out:
-It is a "neutral", "highly resolving" (i.e., cool/clinical/analytical) fuse which crosses over into bright on some recordings. Every note is clearer and more distinct, and subjectively my system plays louder through this fuse without any adjustment in volume.
-Not hearing much difference in soundstage and image dimensions compared with the SR Orange and AHP fuses.
-Decay seems to be slightly truncated compared with the other two fuses.
On balance it doesn't have enough bloom or warmth for my tastes so unless its sound changes dramatically with more burn-in, which I'm not expecting, it will not work for me long term in this application. It should have 100+ hours on it by the time I receive the SR Purple fuse. I will report on it again at that time.