I'm not a corksniffer, i'm a DIYer.. Ive installed metro zero-loss fx loops on most of my amps Evidence that fx loops suck tone? It's because 99% of the fx loops out there aren't built with parts that can handle the full voltage output of a tube gainstage Which leads to them lowering the voltage of the gainstage before the loop to voltages that are abnormal and starve the tone. If you want proof of this just buy a cheap multimeter and measure voltages in-between the last gainstage before the loop in your amp and then the voltages between the first and second gainstage and compare. The less voltage you feed a tube gainstage the more tone it will suck because tubes sound bad at low voltage. The Metro-kit costs $90 and has parts that handle full tube gainstage output voltage. It's hardly corksniffery, check out their forum and ask them.. There are alot of amp builders and DIYers there with an abundance of technical knowledge. I've compared amplifiers with the effectsloop (with nothing in it) and without it (by modifying amps to bypass the fx loop). It's not because I made some amateurish mistake of running a pedal in an effectsloop that sucked tone, jeez..