What is wrong with this recording? (Hungarotron label)

[KikoKentaurus]

Here we have a singular complete recording of A.-L. Couperin's chamber music, which is undoubtedly spectacular and underappreciated collection of pieces. But there's one problem - recording sounds like s***.

If you ever heard classical music before, you probably noticed that something's happening with the tonal balance. Sadly I can't really tell why, so I thought maybe you will help me to correctly name the problem and develop a strategy to fix it in post.

It's 1994, so it's early digital (released on CD) and we cannot blame the digitalization process for that. Funnily enough, all Hungarotron recordings of this specific ensemble (with Miklos Spaniy) in the 90's sound like this.

I will add some reference recordings in the comments.

 

[KikoKentaurus]

Here's a recording which too uses a tangent piano (nah, probably just a piano) as a keyboard:

Can you say that it sounds the same, and if not - what differs it from the first one?

And another one, which is probably fortepiano, but the difference is much more obvious due to it's good balance

 

[JSmith]

Any difference to the CD on Spotify?

JSmith