heard the Aero at Capital Audiofest. Very nice sounding, it was surrounded by top end equipment in several show rooms. Did not hear the Holo. One to consider is Geshelli Labs Dayzee. Also heard at CAF this year, Would say on the same level, maybe not as warm, but you can swap op amps to customize the sound. Still trying to find somewhere to hear the Yggdrasil.
