Also.. doesn't really solve this problem, but did you try using the advanced limiter on the F8? That's how I manage "overly hot mics" into the XLR mic-inputs of F8 version 1. Advanced limiter works same for line-in, which is only via TRS on the original F8 and does not provide optional phantom power. That works for me. I need phantom to the mics and am unable to switch to using line-in which would otherwise solve the problem for me.
I may try that.
Don't want to go too OT on F8 in this 680 thread, but its worth trying. It's somewhat different than a classic limiter and more transparent than most to my ear. Instead of having/setting a traditional engagement threshold level, you instead set a "never to exceed" value.
You will want to set that to 0dB. Turning the advanced limiter on implements a pad (-10dB I think) which is what provides the additional headroom. The limiter then engages progressively, starting ~10db below 0dbFS. So, any material which would not have clipped previously without the limiter remains unaffected (other than a noise floor increase from the pad, which I've not noticed), the limiter only starts working above that point and even when it does it starts off mildly and progressively ramps up the ratio as level increases further to keep the signal from ever exceeding 0dB. That allows it to effectively provide additional headroom without any audible effects when only lightly engaged.
The progressive engagement means its doing little at all when just slightly engaged, but clamps down increasingly strongly as the signal level continues to rise and approaches 0dB. Rather than of an abrupt onset above a threshold setting, it progressively ramps up from a 1:1 ratio (no limiting) to infinity:1 just prior to the signal reaching the targe value, which has been set to 0dBFS.
That's how a digitally implemented / digitally controlled limiter should work IMO. I previously eschewed limiters, and instead just set levels conservatively, but I leave the F8's advanced limiter on all the time. It rarely engages, and I don't worry about it if does.
Recording onstage near drums I have seen it get pushed it all the way up to inf/1 ratio. I can hear the effect on those peaks, but many folks would never notice it, its relatively subtle and waaaay better than outright overload distortion or clipping.