Thiel Owners

There are a few posts with 2.3, 2.4 and Rob being mentioned. I had the coincident drivers in my 2.3i rebuilt by Rob twice - 2006 and 2017. In 2006 they did came back great. However something remarkable happened in the 2017 rebuild - they came back sounding so much better that I was stunned. Everything we love about Thiels became turbocharged and in addition there was now a body and richness to the sound that makes vocals and violin scarily realistic. I encourage 2.3/2.4 owners who might be thinking about an easy upgrade to give him a call.

3rd - Rob Gillum is the man!
He rebuilt my CS2.3 mid/highs in 2017. Now they 1) sound better than new especially the 3D soundstage, 2) are cured of any slight aggressiveness that Thiels may be criticised for and 3) were perfect straight out of the box with no running in required. I have auditioned several current $10,000 speakers and none of them come close to my Thiels. He can surely work magic on the woofers.

coop_301

I have a RME ADI-2 Pro AE powered by a LPS and have tried what you are asking. My system is Bryston/Thiel. RME (with digital volume control disabled by locking it at 0dB) connected to preamp sounds much better than RME (with digital volume control active) directly connected to power amp. 
I have extensively tested the audibility of the RME digital volume control and can assure you it significantly degrades the sound quality, no matter what RME’s designer claims. But even with the digital volume control disabled, I think the RME is too far below the level of your ML/Thiel. A true high-end DAC should nail you to the listening chair until the track finishes. It does not do it for me - I just use it as a headphone DAC/amp for my PC/video editing setup. It is good for the price but is no giant killer.
Best wishes.