Jeez, I think you would bleed from the ears at that point! I have never turned up the master on these amps past four, even at an outdoor gig. And four is just stupid loud. The power amount is total overkill, as these are amps designed for bass reinforcement where that power is getting used, but there is also a lot of built-in headroom. You have to be smart about it.
The load is an interesting part of the equation; this new head I have is rated 375 watts into eight ohms. It will not push a 2-ohm load, although my Focus 2R head will (I am using only the power amp section on these little heads for guitar applications). I wonder if wiring the speakers series instead of parallel would reduce the power output and enable the clipping. I don't know if that would damage anything, though. I had a chance to buy a couple of 16-ohm NOS E-120s a while back.
GenzBenz also makes a 300-watt version of the Shuttle, which is 175 watts into eight ohms. It lacks the tube preamp -- it has an FET circuit instead -- but it does sound nice, as well. Presumably the power section is the same and includes the limiter. That would probably be easier to push to its limits at a small venue. Playing a bass through that 300 watt combo at the store, with an single 10" speaker in an 8-ohm load, it could be pushed very hard without being extremely loud, although it was fairly potent.
I bought this amp primarily as a studio/rehearsal tool for bass -- I got the head, which sells for $699, with its matching 2X10 bass cabinet for just $950 total as a B-stock item -- but I am planning on carrying the head to gigs as a backup amp to my Focus 2R. Playing the Tiger guitar straight into the tube preamp on it and into the E-120s was a pretty decent tone, actually,albeit with the treble control wide open. Well, actually, that's pretty much what Jerry did, come to think of it.
Pretty amazing, with the Focus and the Shuttle, that's a total of 10 pounds of amps, yielding 1400 watts into four ohms. Now, if someone could make a light speaker that sounded as good as those E-120s ...