Are all R2R dacs slow and soft?

I agree with DAC recommendations above. But before you buy a new DAC, you can see if improving your network addresses some of your concerns.  
The long basic Ethernet cable that runs thru walls could be picking up EMI and RFI. When it gets to streamer it just propagates from there to DAC.
This will translate into smeared and harsh sound.
You can a quick test that will be relatively cheap and potentially cost you nothing. Pick up a trendnet 8 port 1G unmanaged switch and a 1m long LinkUp CAT8 ethernet cable and an iFi LAN iSilencer.
Connect your current in wall Ethernet cable to trendnet switch, connect the iFo LAN filter into AirLens and run a Linkup 1m cable from switch into iFi/AirLens.

This should clean up and improve the network feed into AirLens and in turn improve the sound. If it doesn’t, return it all back to amazon. 
But I think you will hear the difference with your components and your speakers. 
 

Switch

Cable

LAN Filter

My Rockna Wavedream Signature does the things you're after. I've owned DACS from MHDT LABS, Aqua, and TEAC. The Rockna would literally startle me sometimes when I first got it due to its drive, dynamics, and detail. It is never bright, unless something else in the system is. As always, system synergy and budget come into play. 

Some.  I just got a dac and when researching, some were eliminated because they were soft, and the measurements seemed to show it.  Not all R2R dacs are that way.  Do searching for brightness - sometimes reducing toe in helps reduce treble energy.  The DAC you have was on my list and based on my reading, I did not consider it bright.  I did not get it, though. 

What’s your budget, and are you looking for new or used?

Under 5.

Either new or used