DAC for Hegel/Thiel System

I'm searching for a DAC in the $5k and under price range to use the DAC loop feature of my Hegel 390 integrated. I have Thiel 2.7 speakers. I typically stream using the Hegel. I'm also using the DAC in the Hegel 390. Everyone says the system sounds great, but as you might expect, it is very accurate, crisp, neutral and sometimes borders on fatiguing depending on the music. I am torn between the highly acclaimed Hegel D50 DAC and the LTA Aero. The LTA would introduce tubes into the chain, a feature  many Thiel fans prefer. I'm not married to these two choices, so any thoughts would be greatly appreciated. Thanks