Thanks for the input!
To clarify, yeah, we're looking at input about the headphone outputs of a hypothetical balanced amp (the fact we're asking this is a clue how early we are in development.) We'd love to leave the dual 3-pin arrangement in the dust, if we can. But if we have to have them, well, there you go.
As far as this cannibalizing the Lyr--nope. Like I said, I'm a fan of balanced, but only balanced done right. Far too many "balanced" amps aren't really balanced, and use things like balanced-to-single-ended conversion, then run through a 2-gang pot, before going to the balanced output stage. Or they're a single-ended amp with a 4-pin connector. Or they're some awful quasi-bridge thing like you'd see in 1970s stereo amps.
Balanced done right is costly--it requires a quad pot (which is not even listed in the Alps catalog anymore, but if you want to buy 1200+ of them, yeah, you can sweet-talk them into it) and real balanced circuitry from input to output. It also requires twice the current (at half the voltage) of a single-ended amp. And if you start getting into, say, circlotron output stages, you're talking about a complex power supply. I guess what I'm trying to say is, well, hell, balanced ain't gonna be cheap.
To bring this more on the DAC topic, the middle (balanced) DAC will be a lot more than a balanced Bifrost, and it'll have a couple of new tricks that I guarantee you haven't seen before on other DACs on the market. So comparing it to Chinese-made, non-upgradable, 16/48 USB-input stuff just ain't fair.