Thank you for sharing your impressions! I've actually been eyeing the A90 to pair with my SendyAudio Aivas as well (source will be the D70). So far I've driven it with the Atom Amp as well as my DX150 with Amp7. What's clear to me is that the Sendys can really scale up with a proper amp - care to share what other amps which you have tried the Sendys with?
Cheers,
Nick
Both the SendyAiva and TinHifi P1 Planars really sound great on the A90. I broke-in both on a FiiO M15 and the extra power on the A90 really makes them sing.
Interestingly I can run the TinHifi P1 on the A90 L, M, H gain and get different POV's (listen of views?) - the sound stage grows, the bass is bigger, the highs are more - so that's what is interesting is I can run L gain under 12 oclock, M gain around 10 (clock face numeral, not 100%!), and H gain at 8-9-10 and they all play with different characteristics - besides being louder or quieter or more or less "full".
I also ran the Sendy Aiva's on BTR5 and BTR3k, 3.5mm SE on BTR3k wasn't adequate. 2.5mm balanced had enough power to enjoy on the BTR3k. On the BTR5 both 3.5mm and 2.5mm were great, of course the extra power on the 2.5mm was best.
There's a lot of air and detail anyway on Planars, but the A90 fills those areas up with detail - even old TV shows like Dr. Who really show the talents of the sound engineers from way back then, and an Indian Scifi I watched had a depth of audio that was really well done.
I am hearing things across all my IEM's and Headphones that weren't there before - the characteristics of all of my headphones have changed for the better through the A90.
Today I was enjoying the normally Blon BL-05 - and that's new for me too, the Blon-05 hasn't been my best listen and now it's enjoyable - more interesting at least.
My SendyAiva's need a little TLC - new pads on the sliders - they aren't holding and it's not comfortable to keep adjusting them on my head right now. I got the pads in the mail and need to replace them with the thicker pads used now in production. I'll spend more time on that this weekend and report back with more hours on them.
That is until the Dunu DK2001's arrive - followed by the KZ AS16's - shoot me, I'm a KZ fan.
I'd wholeheartedly recommend trying the A90 with your Sendy Aiva's - and other hard to drive headphones.
I was already eyeing the DT880 Premium / DT990 - waiting till I had an ampt to drive 600 ohm headphones, then there seems to be a recently resurgence of interest in them. I've heard the A90 has enough power, but if you are an exuberant listener - like myself - you might hit 75% on H Gain...nothing's perfect I guess, but the A90 is close.