You may not like this answer but as a VA Bach Grand owner, here is my opinion based on experience with Viennas..
For the type of music you like with a preference for bass, the Onyko 609 is not a good match for the Haydns. Also you say you prefer not to use a sub. The Haydn, either Grand or SE, is a 4 OHM speaker and at only 89 db sensitivity will require a lot more power and current to show you what they can really do. And why not get the most out of a great pair of speakers, especially at what you are considering to spend on them as indicated in your orginal post. Also if you go this route, and you are not pleased wit the results, your stuck because the Onyko does not have pre-outs for a dedicated amp to power the Haydns. I think the Focal and Paradigms you heard are a much better match with your receiver as they are far more efficient and 8 OHM speakers.
But If you really insist on pairing your AVR with the Haydns, then consider a sub. This will help with the bottom end. Good luck in what ever route you follow.
Marantz PM15S2 LE, Oppo BDP-103, Simaudio Moon 100D DAC
VPI Traveler V2 with an Ortofon Rondo Blue and Simaudio Moon 110LP, Technics SL-1400 with an Audio Technica AT-14sa and Pro-ject Phono Box S
Dynaudio Focus 260's, Rel T-1 and a Panasonic TC-P54S1.