Running the Chord Dave directly into a pair of CAM's is not going ampless; you are using the amplification stage of the Chord (I'm not sure of the topography, perhaps a high quality OP Amp). It is effectively a headphone amp being used as a speaker amp.
A few points:
1. You say that a subwoofer is needed, specifically a JL Audio sub. I will argue that there are other subs that will be at least as fast as the JL Audio, specifically Omega's own sub or those from Rhythmik.
2. 90dB at 1m into a pair of CAM's implies a power of about 0.5wpc at most. Again, we are talking about the level you will get from a headphone amp.
Can the Dave drive a pair of CAM's, even in the nearfield? Sure, but rather than "transparency" I would expect that it would run out of steam. Most music has some significant dynamic passages that create momentary current demands on the amplification stage.
You owe it to yourself to see how they sound with just the Dave and then with a high quality single ended amp, either SEP or SET. Unless you have some very specific sonic preferences, the tube amp will vastly improve the drive to the speaker and make you rethink the "need" for a subwoofer.
Well, to quote Rob Watts, the Creator of DAVE regarding the output of the DAVE:
"So with Dave we have 20 elements that are resistors and flip-flops. So we can have them all on, and in voltage mode the OP would be +5v (the reference voltage) and all off and it would be 0v. With half on and half off we have 2.5v. Now actually I don't use voltage mode as it creates too much distortion - the switching activity propagation delay gets gets modulated by the actual OP voltage - so the resistors go into the single I to V converter. In this case the other input of the I to V is set to 2.5v, so now when they are all on it pushes current (5 mA) into the I to V node, when all off it sucks current (5 mA) out of the node. When current is fed into the node, this is balanced by an equal and opposite current from the OP stage - and due to the feedback resistor, we get an output voltage. Now this will be a noise shaped analogue output, which just needs some gentle filtering to get you analogue that can then drive HP or power amps directly. And the filtering is done by a couple of capacitors in the feedback path.
Simple really.
But getting the I to V node so it was exactly 2.5v under all conditions without RF noise ain't easy. And getting the reference voltage so that that was noise free and never changing was also not easy. Remember that only a 10 nV change in reference voltage that is signal related will create measurable distortion...
Rob"
So, not as a point of contention, but by means of explanation, that's a very sophisticated single OP that's identical from the headphone output at line level to the RCA output. In fact, not to pad the spec sheet, that's nearly an unmeasurable distortions profile of -150db, with noise floor modulation creeping below -180db, which is the furthest an APX555 can measure.
Granted, some of this is me regurgitating what I've learned over time, but a great deal of it has been the proof in the pudding. So, transparent? Yes, I could safely say about as transparent as one could get.
As far as my math, yeah, it could be wildly off. At 3.35 WPC maybe the DAVE can drive the CAMs better than I think. I'm really not into tubes, so that's pretty much out.
But, we will see how it does, won't we? I'm only going off of reports from people driving CAMs and SAMs with DAVE. They gush over it. I don't think I'll be able to reproduce Mahler's 5the with these boxes, but then again, I probably wouldn't want to. Thus the reason I question about the High Output speakers.