Why are my SF Venere S Speakers not sounding as warm?

You have couple serious major issues. First is your electronics and second is your untreated living room.

I wouldn’t run these Sonus Faber Veneer S speakers off a cheap mediocre Marantz SR6012 AV receiver or any AV receivers if I were you. You will not get a full potential of your Sonus Faber speakers by running them off this cheap Marantz SR6012 AV receiver. You will need to upgrade to good quality AV separates. For a budget five-channel power amp I would highly recommend the Rotel RMB-1585 retails for $3k new. This is a five-channel class AB amp. It’s a great sounding and is a high performance amp. It’s a very good amp especially for the money. Another great five-channel amp will be the Parasound Halo A51 retails for $4500 new and IMO it is better than the Rotel RMB-1585.

For an affordable AV pre pro (preamp surround processor) I recommend the Marantz AV8802 or AV8805 or the Anthem AVM60. The Anthem has superior room correction (ARC2) than the Marantz’s Audyssey. The step up in sound quality and audio performance than these Marantz or the Anthem AVM60 will be the Classe Sigma SSP, Krell Foundation series or an older Krell 1200U (long discontinued), Classe SSP 800 (discontinued), NAD M17, Cary Cinema 12. But the Cary Cinema 12 has been well known for their failing HDMI board/switching it sounds really good for both stereo music & surround movies but constantly has been having issues. Seemed like almost every single unit fails after couple yrs of use. HDMI board failure.

The combination of a good quality AV pre pro and a great five-channel amp such as the Rotel RMB-1585 amp will drastically elevate the performance of your system setup to a whole new different level of sonic performance from your Marantz SR6012 av receiver.

Lastly, you will need room treatments for your living room and try to tweak around with speaker placements / positioning. A well treated room coupled with proper speaker placements will make big difference.

My Rotel amp died and I hooked my SF to a denon AV amp I had and they sounded dead.  Purchased  Jolida Hybrid used on Audiogone and the warm magic is back. 

In my opinion, a well designed speaker should not sound bright because of inferior electronics or cables.  Front end equipment can modify the sound of the speaker somewhat but they cannot change the sound such that it will be unacceptably bright.

I have almost the exact same dimensions as the OP including the same vaulted ceiling from 9 to 15’. Bass from the 802D3 is good, but I do use a little boosting on the preamp. That said, I would agree with above that the first place to look is amplification. In addition, for home theater you’re going to want a great sub or 2. I’ve got the SVS SB-16 and my bass is prolific. 

@tice34 

First let me ask you this : are you only doing stereo setup for listening to music only or surrounds for both HT and stereo music? Cause you are using the Marantz SR6012 av receiver so I automatically assumed that you have a surround system setup. 

If you're only doing stereo and use your setup to only listen to stereo music I wouldn't get AV separates, I would recommend getting a good quality stereo integrated amp or good quality stereo preamp + stereo power amp. 
Stereo gears will sound better than multi-channel gears.