I was interested in getting a a90 and d90 se stack. But i still wanna know do i have any other better options. Its big money just wanna be sure i am spending on the best one in that range.
Headphone: akg 371, dt 770 pro, lcd xc music creator closed , hifiman sundara.
Any suggestions is greatly appreciated 
Well “best” might not be the right way to ask.
In terms of measurements and reviews it’s one of the cleanest stacks out there without sounding overly sterile/boring.
As always YMMV
I enjoy my D90/singxer stack a lot for a warmer leaning sound that is still very capable of detail retrieval.
Can’t not have a Schiity rec here, so I’ll forward the Bifrost2/Jot2 as a contender.
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Depending on the headphone, Bifrost 2 + RNHP. That is one of my favorite of all time combinations.
So once you get to this level, different headphones are going to pair with different amps better. So for example, the RNHP is a known good pairing with the LCD-XC, but the Sundara would maybe prefer something more like a Liquid Platinum. So to some extent, “best” kinda depends on what you want to prioritize.
I really liked the BF2 and Singxer SA1 combo.
Out of what’s mentioned, if you wanted to prioritize the lcd xc, I’d really look into the rupert neve rnhp and a schiit bifrost 2 as that’s a great pairing overall imo, but there’s other good options for it too, just depends on what sound you are after. If you wanted to prioritize the sundara, I think a monolith liquid platinum with a denafrips ares ii or bifrost 2 is a good pick there, although that’s expensive to spend only mainly for a sundara (it would still be great with the lcd xc, but I’d personally rather have the neve and bf2 combo there). With your other headphones I’d assume that would more be a secondary priority as those aren’t all that amp picky and not as capable as the other 2.
I guess really the question would come down to what headphones you want to prioritize, if you plan to grab any other higher end headphones in the future, and generally what sonic aspects/characteristics you want to prioritize? At this price point you do have a reasonable amount of potentially worthwhile options, so it would be helpful to narrow things down to better suit your needs/preferences
Piggybacking off here. Would the monolith liquid + bf2 be a good combo for the Arya? (preference for a focus on vocals + soundstage)
Or what combo would you suggest for exploring higher-end ($500-2k) headphones?
Thanks in advance!