I've been searching for a preamp to add to my Thiel & Pass Lab system to " attenuate digital glare" in the 2-7k hz range

I've been looking at the CJ & Rhuma preamps.

Recently, I have read that the BEST preamps all use tube rectifiers and THEY are the ones that give the good, lush high frequencies.



The little dude called Cary AES, amused me the most when I tried that and became one of my most favorable tube preamp designs.

The Backert Labs preamps are pretty amazing, especially at that price. I've heard them in a number of systems and have always been impressed. I am guessing that they have a bright future. Cheers,
I haven't had the pleasure of hearing either of Backert Labs new preamps but I am  familiar with the Backert's and what they look for in sound.  If you are looking for something to ameliorate upper midrange prominence I would look to cj.  The Backerts have always striven for a dynamic, tonally neutral sound.  Not saying there gear would be in anyway bright, just neutral through the audio frequency range.

Consider the Cary SLP-05 tube amplifier with tube rectifier power supply. In my experience it is "lusher" than the CJ. It was Densis Had's no holds barred pre-amp and is a real upgrade from the SLI-80. It is quite detailed and lush at the same time  It has a high output impedance, so you should have a high input impedance on your amp. Had is no longer with Cary, but they still sell and support the SLP-05.

Prima Luna is also popular with many, although I do not have any experience with it.
I’m using a Mapletree Audio Design line stage. 2 chassis with tube rectification. I’ve stopped looking for better. They are custom built in Canada, and not very expensive considering the performance. Check them out here
Good luck! ! !