Old recordings sound poor on my Burmester 232

And please provide a list of bad sounding recordings. This will provide additional insight. 

Has nothing to do with cables, thread is full of BS. 

This is a good example of how a reasonably highly resolving system accentuates the shortcomings of poor recordings. The LTA MicroZOTL Level 3 Pre pairs well with the Aero DAC, but it does not add much warmth, as one might expect from a tube preamp. It probably won’t magically fix harsh mastering. On the other hand, adding a heavily colored tube amp could compromise the clarity of the Burmester.

I’ve experienced a similar situation, but later I realized that what I needed was not warmth, but smoothness and liquidity. Based on my research, you could try a line-transformer passive pre like the Phasemation LT-1000. You can also explore forums to find other potentially suitable options, but I keep seeing reports that transformer-coupled I/O passive units often outperform many tube or active preamps.

You have a 25K integrated amplifier, I think part of your problem is your electronics 

You have a 4K DAC, Not a very high quality streamer, 

Focal kanta 3 are good, But for that amplifier your equipment is the weak link 

I owned a pair of kanta 3, with a Macintosh MA9000 integrated those two were good match but when I upgrade it to D'Agostino monos 

Progression, My speakers were the weak, I also had to upgrade my components 

To get everything humming along with all my cabling when you get a good amplifier you need good matching components and cabling it wouldn't hurt to run a dedicated line also, Yes it's expensive but everything comes and bits and pieces until you get it where you want it, But that burmeister 232 is a hell of a integrated

I had a similar problem with my office solid state rig- some records sounded unpleasant and harsh. I experimented with an eBay buy- a 1996 Audio Research SP-9 preamp with a phono section as they all had back in the day.  All in about $1500. I had to buy some decent RCA cabling as my system was all XLR. The tube preamp warmed up the old recordings nicely and it's relaxed presentation was pleasing to me. I swapped the power amps (Bryston 4B3 to an ARC VT130) with little satisfaction. The SS power amp was way quieter and not as sexy but the bass was much better- tight and strong. Time has been a friend to the Bryston brand. 

The tube gear is noisy compared to the 2025 Bryston amp and BR 20 preamp.  I guess it's a trade-off. Warmer tube sound with some background noise vs. dead quiet SS gear that is colder sounding.

Anyhow- my point is the cheap (by today's standards)  ARC preamp was a welcome addition to my office system- adding that "fireside with friends" feeling to the music.  I want a ref 6 SE now- greedy eyes LOL.

Congrats on that 232. Nice piece!