Bridged classe audio DR9

Been there done that.
Bridging the DR9s will not sound as good as one into that load.
Best ,JohnnyR

Isn't nominal impedance of your speakers 3 ohm? It will appear for each amp as 1.5ohm load assuming best case of flat impedance curve. It might trigger protection since your amp is rated at 2ohms minimum load. Better try if it works for one channel before buying another DR9. Play loud heavy orchestral piece for 30min to check if thermal protection doesn't kick in. Few people reported it happening just after 5 minutes (googled for DR9 and "Bridged").

I had some Calipers many years ago and got excellent results using passive biamping with 2 amps.

Your best option is to passively biamp the speakers with the 2 DR9's.
Use 1 amp for each speaker, using the left channel for bass and right channel for mid/top.
You will need 2 sets of interconnects from your preamp to the power amps or buy a "Y" connector if your preamp does not have 2 outputs.

This configuration will be a substantial improvement as it delivers more current to each driver than 1 amp or bridging the amps.

Thanks.I have been told that the DR9 Was sounding better when bridged than used alone in stereo.

When you bridge an amp, the damping factor is halved, that means the bass will not be as controled. Not worth it.

Cheers George

Thanks a lot for your answers, I have tried both vertical bi amp and bridged mode. The differences are big. The DR9 used in stereo has the sound of valves amps. When bridged you gain bass ,definition and more space (mainly depth).
I finally stayed with bridged mode as I have found it's the best for my configuration, the definition is impressive.
I listen classical music at around 80 db so I don't think it may be a problem.