I'm quite surprised to see that PS Audio Directstream has the analog output with just -70dB of THD&IM. I would immediately discard it as a match for an amp that has -119dB of THD. It may "sound" whatever, but simply, the crescendos will not come out clean at -70dB of distortion and that's not a match to what AHB2 can do. However, i would certainly try it with setting the gain inside it to highest setting (2.8V balanced) and AHB2 at 2V and remove the preamp completely, as PS has a voume control.
Yggdrasil does fare much better at -86dB of distortion, but that's not enough in this case. For me, this too falls into category "it can "sound" whatever", as I can't justify the engineering decisions behind it.
Both of those will definitely have some "sound" to them and it might as well be a "good" one, but I don't seek for that, as that approach requires dealing with "synergy", or matching certain flaws with complimentary flaws hoping to find the sweet spot.
As for the preamp, it's OK at -100dB at 1k, but rising 20dB and more above 3k. That may make it sound artificially "open", and that's not going to go unnoticed with AHB2, becoming too forward and maybe even annoying.
If you want to hear what AHB2 can do, get a Benchmark DAC3L, which has -113dB of distortion with it's massive analog end. It does not need a preamp, as it's analog section works as such. At less than $2k it's a bargain and it sounds right in every way. I stopped comparing it to other DACs when I got to the one that costs 9k Pounds Sterling that sounded like a bad joke in comparison...like jacked up hash in vocals that wanted to pass for "resolution"...
Once that DAC3L/AHB2 pairing is made, it becomes clear that Benchmark gear is not about "Sound" and "Audiophilia". It's not about this kind of bass or that kind of midrange, or even enjoyment. Not at all! Just like SR1a, it doesn't aspire to be liked with all recordings. It's about having an open window into the recorded event and that's all it aspires to.
Having said that, I have a few close audiophile friends of mine that don't like the same kind of sound that I do, including the Benchmarks, so they listen to something else, something I never would go back to again, as I grew out of liking it and justifying it's existence.
Interestingly enough, they like what SR1a does with their gear, and so do I. Not that I would strive for that, but I do get what they are looking for, why they want it and with what kind audiophile exotica they had to use to get it. Still, my empathy doesn't make them care for my advice, as it should be
My friends and I come from opposite ends of the audiophile spectrum, but SR1a works for all of us. And that is a good thing. Like Srajan wrote, if he would want to get different kinds of presentation, he would simply change the preceding electronics and we can all do that.
So, just by looking at the papers, I wouldn't match any of those above with AHB2 and hope that "synergy" will work with AHB2. If that setup has to be there, then you're better off with some other amp, preferably at the warm side of things.
Cheers,
Alex