The switch is flat in the down position, I believe, the middle is -0.5db, the up is +0.5db.
The Daedalus speakers are not fussy about amp topology.The Job is a great amp, and should be great with the speakers, but I've yet to hear ANY amp that didn't sound great with Daedalus, and I've heard a Shindo, Hypex N-Core, Modwright and several others. And yes, you don't need much power; the Shindo was great with 10 WPC, but my N-Cores are 200 WPC. They all sound great but different, with taste and matchups being key. The overall quality of the amp should be top drawer to get the most out of them, of course.
The switch positions are different with different models and vintage, most of the recent dual tweeter models are at full in the middle position and attenuated in the up or down. The single tweeter models are different and also varied depending on the vintage and model. I'm actually quite embarrassed by this.
I consider the full position to be 'flat' and the other two are attenuated, usually that position is either up or middle. the attenuation is only .5db which is almost imperceptible, this is why I would consider all positions flat as there are more variances in room response etc than .5db.
The best option is to listen and decided which position is the 'brightest', that is the one in a good room which is 'flat'. The purpose of the switch is to make minor adjustments for a room without skewing the system, and in a room that is a problem, that .5db change can make a real improvement.
btw, the older pre 2007 DA-1 was +/- 1db but since 2007 that has been about .5db.
My apologies for this confusion, of course if we had a staff of twenty this would have been cleared up long ago with a printed manual etc. (working on that), of course the speakers would cost $80K

We are currently clarifying the switch positions for all models.
thanks for your patience,
lou