I own both the Anedio and Rega, and from my perspective they are close to each other.
This is from many months of listening both on my main rig with Thiel speakers, (both 3.5's and 3.6's) and my headphone rig with Liquid Fire+Audeze LCD2.2's.
The Anedio get a slight advantage in the subtle detail and HF extension, but in the wrong set up that can be a bit sibilant. The Rega very and i mean very slightly warmer and ever so slightly forgiving of CD's badly recorded .
The Rega uses a Wolfson 8742 DAC chip vs Anedio Sabre32. The build quality is excellent on both, Rega has some nice "tweaks" usually left to DIYers. All the capacitors associated with the analogue signal path are Nichicon FG bypassed with MMK polyester capacitors, and low impedance conductive polymer capacitors are used for DAC decoupling. The power supply utilizes a toroidal transformer, fast rectifier diodes and again Nichicon FG capacitors. There is a power supply for the control microcontroller, separate from the digital & analogue audio stages. Special attention being paid to the inter IC control signals ensuring the control data noise is kept to a minimum.
I could live with either as my only DAC in either rig.
I am right now listening to the Rega in my main Thiel 3.6 rig, because this week I converted the Thiels to dual inputs separating the woofer and LF crossover from the rest of the speaker electronically. I use a VTL St85 for the mid and HF, and carver TFM-35 for the LF. Sounds incredible. The new Pink Floyd Dark Side of the Moon Live concert CD from their 1974 Wembley Stadium concert is as close to live as i have heard. after I finish evaluating the Rega with my "new style" Thiels, I am going to put the Anedio back in to see how it sounds.